485BPOS

File Nos. 002-98772

811-04347

AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 21, 2016

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933	x
Pre-Effective Amendment No.	¨
Post-Effective Amendment No. 190	x

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 236	x

GMO TRUST

(Exact Name of Registrant as Specified in Charter)

40 Rowes Wharf, Boston, Massachusetts 02110

(Address of principal executive offices)

617-330-7500

(Registrant’s telephone number, including area code)

J.B. Kittredge, Esq.

GMO Trust

40 Rowes Wharf

Boston, Massachusetts 02110

(Name and address of agent for service)

with a copy to:

Thomas R. Hiller, Esq.

Ropes & Gray LLP

Prudential Tower

800 Boylston Street

Boston, Massachusetts 02199

It is proposed that this filing will become effective:

x Immediately upon filing pursuant to paragraph (b)

¨ On                     , pursuant to paragraph (b)

¨ 60 days after filing pursuant to paragraph (a)(1)

¨ On                     , pursuant to paragraph (a)(1)

¨ 75 days after filing pursuant to paragraph (a)(2)

¨ On                     , pursuant to paragraph (a)(2) of Rule 485.

This filing relates solely to the 34 series of the Registrant listed on the front cover of the GMO Trust Prospectus, dated June 30, 2016 and filed with the Securities and Exchange Commission on June 29, 2016 with Post-Effective Amendment No. 189 under the Securities Act of 1933, as amended, and Amendment No. 235 under the Investment Company Act of 1940, as amended. No information contained herein is intended to amend or supersede any prior filing relating to any other series of the Registrant.

GMO TRUST

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 (the “1933 Act”) and the Investment Company Act of 1940 (the “1940 Act”), each as amended, the Registrant, GMO Trust, certifies that it meets all of the requirements for effectiveness of this Registration Statement under Rule 485(b) under the 1933 Act and has duly caused this Post-Effective Amendment No. 190 under the 1933 Act and Amendment No. 236 under the 1940 Act to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Boston and The Commonwealth of Massachusetts, on the 21^st day of July, 2016.

GMO Trust
By:	SHEPPARD N. BURNETT*
	Sheppard N. Burnett
Title:	Chief Executive Officer;
	Principal Executive Officer

Pursuant to the requirements of the 1933 Act, this Post-Effective Amendment No. 190 to GMO Trust’s Registration Statement under the 1933 Act has been signed below by the following persons in the capacities and on the date indicated.

Signatures	Title	Date
SHEPPARD N. BURNETT* Sheppard N. Burnett	Chief Executive Officer; Principal Executive Officer	July 21, 2016
CARLY CUSHMAN* Carly Cushman	Treasurer; Chief Financial Officer; Chief Accounting Officer; Principal Financial and Accounting Officer	July 21, 2016
PAUL BRAVERMAN* Paul Braverman	Trustee	July 21, 2016
DONALD W. GLAZER* Donald W. Glazer	Trustee	July 21, 2016
J.B. KITTREDGE* J.B. Kittredge	Trustee	July 21, 2016
PETER TUFANO* Peter Tufano	Trustee	July 21, 2016

* By:	/s/ Douglas Y. Charton
	Douglas Y. Charton
	Attorney-in-Fact**

** Pursuant to Power of Attorney for each of Paul Braverman, Donald W. Glazer, J.B. Kittredge and Peter Tufano filed with the SEC as part of Post-Effective Amendment No. 186 to the Registration Statement under the 1933 Act and Amendment No. 232 to the Registration Statement under the 1940 Act on December 1, 2015 and pursuant to Power of Attorney for each of Sheppard N. Burnett and Carly Cushman filed with the SEC as part of Post-Effective Amendment No. 186 to the Registration Statement under the 1933 Act and Amendment No. 232 to the Registration Statement under the 1940 Act on December 1, 2015.

GMO TRUST 2016 ANNUAL UPDATE 485(b) FILING (XBRL)

1

EXHIBIT INDEX

GMO TRUST

Exhibit Ref.	Title of Exhibit
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.INS	XBRL Instance Document
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase
EX-101.SCH	XBRL Taxonomy Extension Schema Document
Other.
1	Certificate of Clerk of the Trust certifying resolution by the Board of Trustees of the Trust required pursuant to Rule 483 under the Securities Act of 1933

EX-99.1

Exhibit 1

GMO TRUST

CERTIFICATE OF CLERK

I, Douglas Y. Charton, hereby certify that I am the duly elected and acting Clerk of GMO Trust, a Massachusetts business trust (the “Trust”), and do hereby further certify as follows:

1. Attached hereto as Exhibit A are true and correct copies of resolutions from the meeting of the Board of Trustees of the Trust (the “Board”) held November 17, 2015 (the “Meeting”). The resolutions were duly adopted by the Board at the Meeting. Such resolutions have not been modified or rescinded since their adoption and are in full force and effect as of the date hereof.

IN WITNESS WHEREOF, I have hereunto set my hand this 21^st day of July, 2016.

By:	/s/ Douglas Y. Charton
Name:	Douglas Y. Charton
Title:	Clerk

Exhibit A

Resolutions of the Board – November 17, 2015

Power of Attorney Authorizations

VOTED:

That each of Megan Bunting, Douglas Y. Charton and Meta S. David is authorized to sign for Sheppard N. Burnett, in his name and in the capacity of Chief Executive Officer and Principal Executive Officer, on behalf of the Trust, the Trust’s Registration Statement on Form N-1A filed with the Securities and Exchange Commission (the “SEC”) and any and all amendments, pursuant to a power of attorney executed by Mr. Burnett.

VOTED:

That each of Megan Bunting, Douglas Y. Charton and Meta S. David is authorized to sign for Carly Cushman, in her name and in the capacity of Treasurer, Chief Financial Officer, Chief Accounting Officer and Principal Financial and Accounting Officer, on behalf of the Trust, the Trust’s Registration Statement on Form N-1A filed with the SEC and any and all amendments, pursuant to a power of attorney executed by Ms. Cushman.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Feb. 29, 2016
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Central Index Key	dei_EntityCentralIndexKey	0000772129
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jun. 30, 2016
Document Effective Date	dei_DocumentEffectiveDate	Jun. 30, 2016
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016

XML

GMO Benchmark-Free Allocation Fund

GMO BENCHMARK-FREE ALLOCATION FUND

Investment objective

Positive total return not “relative” return.

Fees and expenses

The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees - GMO Benchmark-Free Allocation Fund	Class III	Class IV	Class MF
Purchase premium (as a percentage of amount invested)	0.20%	0.20%	0.20%
Redemption fee (as a percentage of amount redeemed)	0.20%	0.20%	0.20%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Benchmark-Free Allocation Fund		Class III		Class IV		Class MF
Management fee	[1]	0.65%		0.65%		0.65%
Shareholder service fee		0.15%	[1]	0.10%	[1]
Supplemental support fee						0.10%	[1],[2]
Other expenses		0.01%		0.01%		0.01%
Acquired fund fees and expenses (underlying fund expenses)	[3]	0.28%		0.28%		0.28%
Total annual fund operating expenses		1.09%		1.04%		1.04%
Expense reimbursement/waiver	[1]	(0.15%)		(0.15%)		(0.18%)	[2]
Total annual fund operating expenses	[4]	0.94%		0.89%		0.86%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The amounts shown reflect applicable expense reimbursements and waivers noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example - GMO Benchmark-Free Allocation Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	136	382	647	1,404
Class IV	131	366	620	1,347
Class MF	128	363	617	1,344

If you do not sell your shares

Expense Example, No Redemption - GMO Benchmark-Free Allocation Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	116	360	623	1,375
Class IV	111	344	596	1,317
Class MF	108	341	593	1,315

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (including the accounts of Implementation Fund through the period ended July 31, 2015, during which the Fund was consolidated with Implementation Fund, and excluding short-term investments) was 53% of the average value of its portfolio.

Principal investment strategies

The Fund seeks annualized returns of 5% (net of fees) above the Consumer Price Index and annualized volatility (standard deviation) of 5-10%, each over a complete market cycle. GMO does not manage the Fund to, or control the Fund’s risk relative to, any securities index or securities benchmark.

GMO seeks to achieve the Fund’s investment objective by investing in asset classes GMO believes offer the most attractive return and risk opportunities. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund’s allocations to various asset classes. An important component of those forecasts is GMO’s expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. The factors GMO considers and investment methods GMO uses can change over time.

The Fund is structured as a fund of funds and gains its investment exposures primarily by investing in Implementation Fund. In addition, the Fund may invest in any other GMO Fund (together with Implementation Fund, the “underlying GMO Funds”), whether now existing or created in the future. These underlying GMO Funds may include, among others, Alpha Only Fund, Debt Opportunities Fund, Emerging Country Debt Fund, Special Opportunities Fund, and SGM Major Markets Fund (see “Additional Information About the Funds’ Investment Strategies, Risks, and Expenses — Asset Allocation Funds”). Implementation Fund is permitted to invest in any asset class. The Fund also may invest directly in securities (including other underlying funds) and derivatives.

The Fund is permitted to invest (directly or through Implementation Fund or other underlying GMO Funds) in any asset class (including, for example, U.S. and non-U.S. equities (including emerging country equities), U.S. and non-U.S. fixed income securities (including emerging country debt securities), real estate, and commodities), sector, country, or region, and at times may have substantial exposure to a single asset class, sector, country, or region. In addition, the Fund is not restricted in its exposure to any particular market and may invest in securities of companies of any market capitalization, credit quality (including below investment grade securities (commonly referred to as “junk bonds”)), maturity or duration. The Fund may have indirect exposure to derivatives and short sales through its investment in Implementation Fund and the other underlying GMO Funds. GMO’s ability to shift investments within Implementation Fund and between it and the other underlying GMO Funds is not subject to any limits.

Prior to January 1, 2012, the Fund served as a principal component of a broader GMO real return strategy that also included a pooled investment vehicle with a cash-like benchmark. Since January 1, 2012, the Fund has been managed as a standalone investment.

In seeking to achieve the Fund’s investment objective, GMO may invest a significant portion of the Fund’s net assets in cash and cash equivalents. GMO would not consider such investments to be “temporary defensive positions.”

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.”

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results (including the annualized volatility and the annualized returns above the Consumer Price Index that the Fund seeks). In addition, the Fund could produce results consistent with annualized volatility over a complete market cycle yet experience shorter periods of significantly higher or lower volatility. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Futures Contracts Risk – The risk of loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile and the use of futures contracts may increase the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time and the Fund might be unable to effect closing transactions to terminate its exposure to the contract. If the Fund uses futures contracts for hedging purposes, it runs the risk of imperfect correlation between changes in the prices of the contracts and changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are the subject of the hedge. In addition, the Fund may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts may be less liquid and more volatile than U.S. contracts.

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected.

• Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner.

• Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Year Index and the Consumer Price Index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 9.19% (2Q2009)
Lowest Quarter: – 6.90% (4Q2008)
Year-to-Date (as of 3/31/16): 0.16%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Benchmark-Free Allocation Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	[1]	(4.67%)	4.07%	5.60%	8.77%	Jul. 23, 2003
Class III | Return After Taxes on Distributions	[1]	(5.34%)	3.32%	3.89%	6.86%	Jul. 23, 2003
Class III | Return After Taxes on Distributions and Sale of Fund Shares	[1]	(2.48%)	2.98%	4.02%	6.65%	Jul. 23, 2003
Class III | Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes)	[1]	(0.52%)	1.64%	3.51%	3.76%	Jul. 23, 2003
Class III | Consumer Price Index (reflects no deduction for fees, expenses, or taxes)	[1]	0.72%	1.55%	1.87%	2.10%	Jul. 23, 2003
Class IV		(4.61%)			2.58%	Dec. 11, 2012
Class IV | Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes)		(0.52%)			(1.92%)	Dec. 11, 2012
Class IV | Consumer Price Index (reflects no deduction for fees, expenses, or taxes)		0.72%			0.96%	Dec. 11, 2012
Class MF		(4.60%)			3.00%	Mar. 01, 2012
Class MF | Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes)		(0.52%)			(0.55%)	Mar. 01, 2012
Class MF | Consumer Price Index (reflects no deduction for fees, expenses, or taxes)		0.72%			1.06%	Mar. 01, 2012

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees. GMO also has contractually agreed to waive or reduce, through at least June 30, 2017, the Fund's management, shareholder service, and supplemental support fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds").

[2] GMO has contractually agreed to reduce the rate of the supplemental support fees charged each month to the Fund's Class MF shares based on the net assets attributable to Class MF shares as of the last business day of the preceding month based on the following schedule: 0.10% on the first $6 billion of net assets, 0.05% on the next $2 billion, 0.03% on the next $2 billion, and 0.01% thereafter; provided, however, that the effective rate charged at any time will not be reduced to less than 0.06% of Class MF's average daily net assets. This rate will be calculated before giving effect to any other reduction or waiver. This reduction will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] These indirect expenses include interest expense and dividend expenses on short sales that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense, dividend expenses on short sales and transaction fees), indirect interest expense, indirect dividend expenses on short sales and indirect transaction fees were approximately 0.15%, less than 0.01%, 0.05% and 0.08%, respectively.

[4] after expense reimbursement/waiver (Fund and underlying fund expenses)

[1] The returns shown for periods prior to January 1, 2012 are for Class III shares of the Fund under the Fund's prior fee arrangement. Under the Fund's current fee arrangement, the returns for periods prior to January 1, 2012 would have been lower.

[1] The returns shown for periods prior to January 1, 2012 are for Class III shares of the Fund under the Fund's prior fee arrangement. Under the Fund's current fee arrangement, the returns for periods prior to January 1, 2012 would have been lower.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Benchmark-Free Allocation Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO BENCHMARK-FREE ALLOCATION FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Positive total return not “relative” return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (including the accounts of Implementation Fund through the period ended July 31, 2015, during which the Fund was consolidated with Implementation Fund, and excluding short-term investments) was 53% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	53.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The amounts shown reflect applicable expense reimbursements and waivers noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks annualized returns of 5% (net of fees) above the Consumer Price Index and annualized volatility (standard deviation) of 5-10%, each over a complete market cycle. GMO does not manage the Fund to, or control the Fund’s risk relative to, any securities index or securities benchmark. GMO seeks to achieve the Fund’s investment objective by investing in asset classes GMO believes offer the most attractive return and risk opportunities. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund’s allocations to various asset classes. An important component of those forecasts is GMO’s expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. The factors GMO considers and investment methods GMO uses can change over time. The Fund is structured as a fund of funds and gains its investment exposures primarily by investing in Implementation Fund. In addition, the Fund may invest in any other GMO Fund (together with Implementation Fund, the “underlying GMO Funds”), whether now existing or created in the future. These underlying GMO Funds may include, among others, Alpha Only Fund, Debt Opportunities Fund, Emerging Country Debt Fund, Special Opportunities Fund, and SGM Major Markets Fund (see “Additional Information About the Funds’ Investment Strategies, Risks, and Expenses — Asset Allocation Funds”). Implementation Fund is permitted to invest in any asset class. The Fund also may invest directly in securities (including other underlying funds) and derivatives. The Fund is permitted to invest (directly or through Implementation Fund or other underlying GMO Funds) in any asset class (including, for example, U.S. and non-U.S. equities (including emerging country equities), U.S. and non-U.S. fixed income securities (including emerging country debt securities), real estate, and commodities), sector, country, or region, and at times may have substantial exposure to a single asset class, sector, country, or region. In addition, the Fund is not restricted in its exposure to any particular market and may invest in securities of companies of any market capitalization, credit quality (including below investment grade securities (commonly referred to as “junk bonds”)), maturity or duration. The Fund may have indirect exposure to derivatives and short sales through its investment in Implementation Fund and the other underlying GMO Funds. GMO’s ability to shift investments within Implementation Fund and between it and the other underlying GMO Funds is not subject to any limits. Prior to January 1, 2012, the Fund served as a principal component of a broader GMO real return strategy that also included a pooled investment vehicle with a cash-like benchmark. Since January 1, 2012, the Fund has been managed as a standalone investment. In seeking to achieve the Fund’s investment objective, GMO may invest a significant portion of the Fund’s net assets in cash and cash equivalents. GMO would not consider such investments to be “temporary defensive positions.” The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.” Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results (including the annualized volatility and the annualized returns above the Consumer Price Index that the Fund seeks). In addition, the Fund could produce results consistent with annualized volatility over a complete market cycle yet experience shorter periods of significantly higher or lower volatility. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Futures Contracts Risk – The risk of loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile and the use of futures contracts may increase the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time and the Fund might be unable to effect closing transactions to terminate its exposure to the contract. If the Fund uses futures contracts for hedging purposes, it runs the risk of imperfect correlation between changes in the prices of the contracts and changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are the subject of the hedge. In addition, the Fund may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts may be less liquid and more volatile than U.S. contracts. Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner. Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Year Index and the Consumer Price Index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Year Index and the Consumer Price Index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 9.19% (2Q2009) Lowest Quarter: – 6.90% (4Q2008) Year-to-Date (as of 3/31/16): 0.16%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Benchmark-Free Allocation Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.20%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.20%
Management fee	rr_ManagementFeesOverAssets	0.65%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Supplemental support fee	rr_Component1OtherExpensesOverAssets
Other expenses	rr_OtherExpensesOverAssets	0.01%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.28%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.09%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.15%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.94%	[3]
1 Year	rr_ExpenseExampleYear01	$ 136
3 Years	rr_ExpenseExampleYear03	382
5 Years	rr_ExpenseExampleYear05	647
10 Years	rr_ExpenseExampleYear10	1,404
1 Year	rr_ExpenseExampleNoRedemptionYear01	116
3 Years	rr_ExpenseExampleNoRedemptionYear03	360
5 Years	rr_ExpenseExampleNoRedemptionYear05	623
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,375
2006	rr_AnnualReturn2006	12.93%	[4]
2007	rr_AnnualReturn2007	11.28%	[4]
2008	rr_AnnualReturn2008	(11.23%)	[4]
2009	rr_AnnualReturn2009	20.65%	[4]
2010	rr_AnnualReturn2010	4.91%	[4]
2011	rr_AnnualReturn2011	3.86%	[4]
2012	rr_AnnualReturn2012	10.01%	[4]
2013	rr_AnnualReturn2013	10.73%	[4]
2014	rr_AnnualReturn2014	1.21%	[4]
2015	rr_AnnualReturn2015	(4.28%)	[4]
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.16%	[4]
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	9.19%	[4]
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(6.90%)	[4]
1 Year	rr_AverageAnnualReturnYear01	(4.67%)	[4]
5 Years	rr_AverageAnnualReturnYear05	4.07%	[4]
10 Years	rr_AverageAnnualReturnYear10	5.60%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	8.77%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 23, 2003	[4]
GMO Benchmark-Free Allocation Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.20%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.20%
Management fee	rr_ManagementFeesOverAssets	0.65%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[1]
Supplemental support fee	rr_Component1OtherExpensesOverAssets
Other expenses	rr_OtherExpensesOverAssets	0.01%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.28%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.04%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.15%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.89%	[3]
1 Year	rr_ExpenseExampleYear01	$ 131
3 Years	rr_ExpenseExampleYear03	366
5 Years	rr_ExpenseExampleYear05	620
10 Years	rr_ExpenseExampleYear10	1,347
1 Year	rr_ExpenseExampleNoRedemptionYear01	111
3 Years	rr_ExpenseExampleNoRedemptionYear03	344
5 Years	rr_ExpenseExampleNoRedemptionYear05	596
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,317
1 Year	rr_AverageAnnualReturnYear01	(4.61%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	2.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 11, 2012
GMO Benchmark-Free Allocation Fund | Class MF
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.20%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.20%
Management fee	rr_ManagementFeesOverAssets	0.65%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets
Supplemental support fee	rr_Component1OtherExpensesOverAssets	0.10%	[1],[5]
Other expenses	rr_OtherExpensesOverAssets	0.01%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.28%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.04%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.18%)	[1],[5]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.86%	[3]
1 Year	rr_ExpenseExampleYear01	$ 128
3 Years	rr_ExpenseExampleYear03	363
5 Years	rr_ExpenseExampleYear05	617
10 Years	rr_ExpenseExampleYear10	1,344
1 Year	rr_ExpenseExampleNoRedemptionYear01	108
3 Years	rr_ExpenseExampleNoRedemptionYear03	341
5 Years	rr_ExpenseExampleNoRedemptionYear05	593
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,315
1 Year	rr_AverageAnnualReturnYear01	(4.60%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	3.00%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2012
GMO Benchmark-Free Allocation Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(5.34%)	[4]
5 Years	rr_AverageAnnualReturnYear05	3.32%	[4]
10 Years	rr_AverageAnnualReturnYear10	3.89%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	6.86%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 23, 2003	[4]
GMO Benchmark-Free Allocation Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.48%)	[4]
5 Years	rr_AverageAnnualReturnYear05	2.98%	[4]
10 Years	rr_AverageAnnualReturnYear10	4.02%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	6.65%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 23, 2003	[4]
GMO Benchmark-Free Allocation Fund | Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.52%)	[4]
5 Years	rr_AverageAnnualReturnYear05	1.64%	[4]
10 Years	rr_AverageAnnualReturnYear10	3.51%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	3.76%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 23, 2003	[4]
GMO Benchmark-Free Allocation Fund | Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.52%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(1.92%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 11, 2012
GMO Benchmark-Free Allocation Fund | Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes) | Class MF
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.52%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(0.55%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2012
GMO Benchmark-Free Allocation Fund | Consumer Price Index (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.72%	[4]
5 Years	rr_AverageAnnualReturnYear05	1.55%	[4]
10 Years	rr_AverageAnnualReturnYear10	1.87%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	2.10%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 23, 2003	[4]
GMO Benchmark-Free Allocation Fund | Consumer Price Index (reflects no deduction for fees, expenses, or taxes) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.72%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.96%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 11, 2012
GMO Benchmark-Free Allocation Fund | Consumer Price Index (reflects no deduction for fees, expenses, or taxes) | Class MF
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.72%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.06%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2012

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees. GMO also has contractually agreed to waive or reduce, through at least June 30, 2017, the Fund's management, shareholder service, and supplemental support fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds").

[2] These indirect expenses include interest expense and dividend expenses on short sales that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense, dividend expenses on short sales and transaction fees), indirect interest expense, indirect dividend expenses on short sales and indirect transaction fees were approximately 0.15%, less than 0.01%, 0.05% and 0.08%, respectively.

[3] after expense reimbursement/waiver (Fund and underlying fund expenses)

[4] The returns shown for periods prior to January 1, 2012 are for Class III shares of the Fund under the Fund's prior fee arrangement. Under the Fund's current fee arrangement, the returns for periods prior to January 1, 2012 would have been lower.

[5] GMO has contractually agreed to reduce the rate of the supplemental support fees charged each month to the Fund's Class MF shares based on the net assets attributable to Class MF shares as of the last business day of the preceding month based on the following schedule: 0.10% on the first $6 billion of net assets, 0.05% on the next $2 billion, 0.03% on the next $2 billion, and 0.01% thereafter; provided, however, that the effective rate charged at any time will not be reduced to less than 0.06% of Class MF's average daily net assets. This rate will be calculated before giving effect to any other reduction or waiver. This reduction will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

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GMO Global Asset Allocation Fund

GMO GLOBAL ASSET ALLOCATION FUND

Investment objective

Total return greater than that of its benchmark, the GMO Global Asset Allocation Index, an internally maintained index computed by GMO, consisting of 65% MSCI ACWI and 35% Barclays U.S. Aggregate Index.

Fees and expenses

The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees	GMO Global Asset Allocation Fund Class III
Purchase premium (as a percentage of amount invested)	0.15%
Redemption fee (as a percentage of amount redeemed)	0.15%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Global Asset Allocation Fund Class III
Management fee	none
Shareholder service fee	none
Other expenses	0.01%
Acquired fund fees and expenses (underlying fund expenses)	0.54%	[1]
Total annual fund operating expenses	0.55%
Expense reimbursement	(0.01%)	[2]
Total annual fund operating expenses	0.54%	[3]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Global Asset Allocation Fund | Class III | USD ($)	86	216	357	770

If you do not sell your shares

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Global Asset Allocation Fund | Class III | USD ($)	70	199	339	747

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 20% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 14% of the average value of its portfolio.

Principal investment strategies

The Fund is a fund of funds and invests primarily in shares of other series of GMO Trust (collectively, the “underlying GMO Funds”), which may include the Equity Funds, the Fixed Income Funds, the Implementation Funds, and SGM Major Markets Fund (see “Additional Information About the Funds’ Investment Strategies, Risks, and Expenses — Asset Allocation Funds”). The Fund also may invest directly in securities (including other underlying funds) and derivatives.

The Fund is permitted to invest in any asset class, including, for example, U.S. and non-U.S. equities (including emerging country equities), U.S. and non-U.S. fixed income securities of any credit quality, including below investment grade securities (commonly referred to as “junk bonds”) (including emerging country debt securities) and commodities. The term “equities” refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The Fund may invest in securities of companies of any market capitalization.

GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to select the underlying GMO Funds in which the Fund invests and to decide how much to invest in each. An important component of those forecasts is GMO’s expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund’s holdings of the underlying GMO Funds in response to changes in GMO’s investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund’s investments. Under normal circumstances, GMO intends to invest not more than 85% of the Fund’s assets in the Equity Funds. The factors GMO considers and investment methods GMO uses can change over time.

The Fund also may invest in money market funds unaffiliated with GMO or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.”

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Futures Contracts Risk – The risk of loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile and the use of futures contracts may increase the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time and the Fund might be unable to effect closing transactions to terminate its exposure to the contract. If the Fund uses futures contracts for hedging purposes, it runs the risk of imperfect correlation between changes in the prices of the contracts and changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are the subject of the hedge. In addition, the Fund may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts may be less liquid and more volatile than U.S. contracts.

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee.

• Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of broad-based indices and the Fund’s benchmark (which is a composite index computed by GMO). Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 11.72% (2Q2009)
Lowest Quarter: – 9.48% (4Q2008)
Year-to-Date (as of 3/31/16): 1.69%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Global Asset Allocation Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	[1]	(4.56%)	4.08%	4.65%	6.96%	Jun. 28, 1996
Class III | Return After Taxes on Distributions	[1]	(6.79%)	2.74%	3.00%	4.98%	Jun. 28, 1996
Class III | Return After Taxes on Distributions and Sale of Fund Shares	[1]	(1.22%)	3.09%	3.40%	5.06%	Jun. 28, 1996
MSCI ACWI (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	[1]	(2.36%)	6.09%	4.76%	5.74%	Jun. 28, 1996
Barclays U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes)	[1]	0.55%	3.25%	4.52%	5.54%	Jun. 28, 1996
GMO Global Asset Allocation Index (Fund benchmark)	[1]	(1.13%)	5.30%	4.80%	5.17%	Jun. 28, 1996

[1] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.49%, less than 0.01%, and 0.05%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

[1] The Fund commenced operations on June 28, 1996 with two classes of shares – Class I shares and Class II shares. No Class II shares were outstanding as of October 16, 1996. Class III shares were first issued on October 22, 1996. Class I shares converted to Class III shares on January 9, 1998. Class III performance information presented in the table represents Class II performance from June 28, 1996 to October 16, 1996, Class I performance from October 16, 1996 to October 21, 1996, and Class III performance thereafter. The performance information (before and after taxes) for all periods prior to June 30, 2002 was achieved prior to the change in the Fund's principal investment strategies, effective June 30, 2002.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Global Asset Allocation Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO GLOBAL ASSET ALLOCATION FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return greater than that of its benchmark, the GMO Global Asset Allocation Index, an internally maintained index computed by GMO, consisting of 65% MSCI ACWI and 35% Barclays U.S. Aggregate Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 20% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 14% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	20.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund is a fund of funds and invests primarily in shares of other series of GMO Trust (collectively, the “underlying GMO Funds”), which may include the Equity Funds, the Fixed Income Funds, the Implementation Funds, and SGM Major Markets Fund (see “Additional Information About the Funds’ Investment Strategies, Risks, and Expenses — Asset Allocation Funds”). The Fund also may invest directly in securities (including other underlying funds) and derivatives. The Fund is permitted to invest in any asset class, including, for example, U.S. and non-U.S. equities (including emerging country equities), U.S. and non-U.S. fixed income securities of any credit quality, including below investment grade securities (commonly referred to as “junk bonds”) (including emerging country debt securities) and commodities. The term “equities” refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The Fund may invest in securities of companies of any market capitalization. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to select the underlying GMO Funds in which the Fund invests and to decide how much to invest in each. An important component of those forecasts is GMO’s expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund’s holdings of the underlying GMO Funds in response to changes in GMO’s investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund’s investments. Under normal circumstances, GMO intends to invest not more than 85% of the Fund’s assets in the Equity Funds. The factors GMO considers and investment methods GMO uses can change over time. The Fund also may invest in money market funds unaffiliated with GMO or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.” Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Futures Contracts Risk – The risk of loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile and the use of futures contracts may increase the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time and the Fund might be unable to effect closing transactions to terminate its exposure to the contract. If the Fund uses futures contracts for hedging purposes, it runs the risk of imperfect correlation between changes in the prices of the contracts and changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are the subject of the hedge. In addition, the Fund may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts may be less liquid and more volatile than U.S. contracts. Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee. Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of broad-based indices and the Fund’s benchmark (which is a composite index computed by GMO). Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of broad-based indices and the Fund’s benchmark (which is a composite index computed by GMO).
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 11.72% (2Q2009) Lowest Quarter: – 9.48% (4Q2008) Year-to-Date (as of 3/31/16): 1.69%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Global Asset Allocation Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.15%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.15%
Management fee	rr_ManagementFeesOverAssets	none
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.01%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.54%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.55%
Expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.54%	[3]
1 Year	rr_ExpenseExampleYear01	$ 86
3 Years	rr_ExpenseExampleYear03	216
5 Years	rr_ExpenseExampleYear05	357
10 Years	rr_ExpenseExampleYear10	770
1 Year	rr_ExpenseExampleNoRedemptionYear01	70
3 Years	rr_ExpenseExampleNoRedemptionYear03	199
5 Years	rr_ExpenseExampleNoRedemptionYear05	339
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 747
2006	rr_AnnualReturn2006	12.11%
2007	rr_AnnualReturn2007	8.58%
2008	rr_AnnualReturn2008	(19.38%)
2009	rr_AnnualReturn2009	22.39%
2010	rr_AnnualReturn2010	7.38%
2011	rr_AnnualReturn2011	1.67%
2012	rr_AnnualReturn2012	10.40%
2013	rr_AnnualReturn2013	12.54%
2014	rr_AnnualReturn2014	1.31%
2015	rr_AnnualReturn2015	(4.27%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	1.69%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	11.72%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(9.48%)
1 Year	rr_AverageAnnualReturnYear01	(4.56%)	[4]
5 Years	rr_AverageAnnualReturnYear05	4.08%	[4]
10 Years	rr_AverageAnnualReturnYear10	4.65%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	6.96%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 1996	[4]
GMO Global Asset Allocation Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(6.79%)	[4]
5 Years	rr_AverageAnnualReturnYear05	2.74%	[4]
10 Years	rr_AverageAnnualReturnYear10	3.00%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	4.98%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 1996	[4]
GMO Global Asset Allocation Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(1.22%)	[4]
5 Years	rr_AverageAnnualReturnYear05	3.09%	[4]
10 Years	rr_AverageAnnualReturnYear10	3.40%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	5.06%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 1996	[4]
GMO Global Asset Allocation Fund | MSCI ACWI (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.36%)	[4]
5 Years	rr_AverageAnnualReturnYear05	6.09%	[4]
10 Years	rr_AverageAnnualReturnYear10	4.76%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	5.74%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 1996	[4]
GMO Global Asset Allocation Fund | Barclays U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.55%	[4]
5 Years	rr_AverageAnnualReturnYear05	3.25%	[4]
10 Years	rr_AverageAnnualReturnYear10	4.52%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	5.54%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 1996	[4]
GMO Global Asset Allocation Fund | GMO Global Asset Allocation Index (Fund benchmark)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(1.13%)	[4]
5 Years	rr_AverageAnnualReturnYear05	5.30%	[4]
10 Years	rr_AverageAnnualReturnYear10	4.80%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	5.17%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 28, 1996	[4]

[1] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.49%, less than 0.01%, and 0.05%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

[4] The Fund commenced operations on June 28, 1996 with two classes of shares – Class I shares and Class II shares. No Class II shares were outstanding as of October 16, 1996. Class III shares were first issued on October 22, 1996. Class I shares converted to Class III shares on January 9, 1998. Class III performance information presented in the table represents Class II performance from June 28, 1996 to October 16, 1996, Class I performance from October 16, 1996 to October 21, 1996, and Class III performance thereafter. The performance information (before and after taxes) for all periods prior to June 30, 2002 was achieved prior to the change in the Fund's principal investment strategies, effective June 30, 2002.

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GMO SGM Major Markets Fund

GMO SGM MAJOR MARKETS FUND

(formerly known as GMO Systematic Global Macro Opportunity Fund)

Investment objective

Long-term total return.

Fees and expenses

The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO SGM Major Markets Fund		Class III	Class IV	Class VI
Management fee	[1],[2]	0.85%	0.85%	0.85%
Shareholder service fee	[1]	0.15%	0.10%	0.055%
Other expenses		0.04%	0.04%	0.04%
Total annual fund operating expenses		1.04%	0.99%	0.95%
Expense reimbursement/waiver	[1]	(0.03%)	(0.03%)	(0.03%)
Total annual fund operating expenses	[3]	1.01%	0.96%	0.92%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - GMO SGM Major Markets Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	103	337	589	1,311
Class IV	98	321	562	1,253
Class VI	94	308	540	1,207

Expense Example, No Redemption - GMO SGM Major Markets Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	103	337	589	1,311
Class IV	98	321	562	1,253
Class VI	94	308	540	1,207

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (including the accounts of the Fund’s wholly-owned subsidiary, GMO Alternative Asset SPC Ltd., and excluding short-term investments) was 29% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016 (including the accounts of GMO Alternative Asset SPC Ltd., and excluding short-term investments and transactions in U.S. Treasury Fund), was 1% of the average value of its portfolio.

Principal investment strategies

The Fund's benchmark is the Citigroup 3-Month Treasury Bill Index. The Fund seeks annualized returns of 5% (gross of fees) above the Citigroup 3-Month Treasury Bill Index and annualized volatility (standard deviation) of approximately 6-10%, each over a complete market cycle. The Fund does not maintain a specified interest rate duration for its portfolio.

The Fund typically takes long and short positions in a range of global equity, bond, currency, and commodity markets using exchange-traded futures and forward non-U.S. exchange contracts, as well as making other investments. The Fund seeks to take advantage of GMO's proprietary investment models for global tactical asset allocation and equity, bond, currency, and commodity market selection.

The Fund normally invests assets not held as margin for futures or forward transactions in cash directly (e.g., Treasury bills, Treasury floating rate notes, Treasury Separately Traded Registered Interest and Principal Securities ("STRIPS"), Federal Home Loan Bank discount notes, and other agency notes), money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds. The Fund also may invest in U.S. and non-U.S. fixed income securities of any credit quality (including below investment grade securities (commonly referred to as "junk bonds")), maturity or duration and in shares of U.S. Treasury Fund.

GMO's models for this systematic process are based on the following strategies:

• Value-Based Strategies. Value factors compare the price of an asset class or market to an economic fundamental value. Generally, value strategies include yield analysis and mean reversion analysis.

• Sentiment-Based Strategies. Generally, sentiment-based strategies assess factors such as risk aversion, analyst behavior, and momentum.

In implementing the Fund's investment strategy, GMO seeks to take risk positions that, in GMO's view, are proportionate to the return opportunities. As a result, during time periods when GMO believes the return opportunities are high relative to the risks involved, the Fund may take more risk relative to the Fund's benchmark. Conversely, during time periods when GMO believes the return opportunities are low relative to the risks involved, the Fund may take less risk (or no risk) relative to the Fund's benchmark.

GMO may eliminate strategies or add new strategies in response to additional research, changing market conditions, or other factors. The factors GMO considers and investment methods GMO uses can change over time.

The Fund may gain exposure to commodities and some other asset classes by investing through a wholly-owned subsidiary advised by GMO, which does not receive any additional management or other fees for its services. The subsidiary invests primarily in commodity-related derivatives and fixed income securities but also may gain exposure to any other investment in which the Fund is permitted to invest directly. References in this Prospectus to the Fund may refer to actions undertaken by the subsidiary as well as the Fund. The Fund does not invest directly in commodities and commodity-related derivatives, but may do so indirectly through its subsidiary (or otherwise).

The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. An investment in the Fund is subject to different risks, and greater overall risk, than an investment in the components of the Fund’s benchmark. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in its wholly-owned subsidiary and in underlying funds. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in its wholly-owned subsidiary and in underlying funds, see “Description of Principal Risks.”

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results (including the annualized volatility and the annualized returns above the Citigroup 3-Month Treasury Bill Index that the Fund seeks). In addition, the Fund could produce results consistent with annualized volatility over a complete market cycle yet experience shorter periods of significantly higher or lower volatility. GMO often uses quantitative models as part of its investment process, and relies heavily on those models in making investment decisions for the Fund. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner.

• Futures Contracts Risk – The risk of loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile and the use of futures contracts may increase the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time and the Fund might be unable to effect closing transactions to terminate its exposure to the contract. If the Fund uses futures contracts for hedging purposes, it runs the risk of imperfect correlation between changes in the prices of the contracts and changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are the subject of the hedge. In addition, the Fund may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts may be less liquid and more volatile than U.S. contracts.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of its investment in its wholly-owned subsidiary and the underlying funds in which it invests, including the risk that its wholly-owned subsidiary and those underlying funds will not perform as expected.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index and a composite index computed by GMO. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance. Prior to October 3, 2011, the Fund was managed pursuant to a materially different investment strategy and would have achieved materially different performance results under its current investment strategy from that shown for periods prior to October 3, 2011.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 12.14% (4Q2010)
Lowest Quarter: – 22.27% (4Q2008)
Year-to-Date (as of 3/31/16): 0.55%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO SGM Major Markets Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class III		0.37%	0.62%	1.97%	2.61%	Apr. 11, 2005
Class III | Return After Taxes on Distributions	[1]	0.37%	0.62%	1.97%	2.61%	Apr. 11, 2005
Class III | Return After Taxes on Distributions and Sale of Fund Shares	[1]	0.21%	0.48%	1.53%	2.05%	Apr. 11, 2005
Citigroup 3-Month Treasury Bill Index (Fund benchmark) (reflects no deduction for fees, expenses, or taxes)		0.03%	0.05%	1.17%	1.31%	Apr. 11, 2005
Citigroup 3-Month Treasury Bill Index +++ (Composite Index)		0.03%	(1.30%)	0.76%	1.36%	Apr. 11, 2005

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero as a result of this waiver. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] The amount has been restated to reflect current management fees.

[3] after expense reimbursement/waiver

[1] After-tax returns do not reflect distributions made by the Fund for all periods prior to December 1, 2015, the date on which the Fund elected to change its U.S. federal income tax status from that of a partnership to a corporation. Further, as described in "Distributions and Taxes," the Fund intends to elect to be treated and to qualify and be treated each year as a regulated investment company under Subchapter M of the Internal Revenue Code of 1986, as amended, for U.S. federal income tax purposes.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO SGM Major Markets Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO SGM MAJOR MARKETS FUND (formerly known as GMO Systematic Global Macro Opportunity Fund)
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Long-term total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (including the accounts of the Fund’s wholly-owned subsidiary, GMO Alternative Asset SPC Ltd., and excluding short-term investments) was 29% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016 (including the accounts of GMO Alternative Asset SPC Ltd., and excluding short-term investments and transactions in U.S. Treasury Fund), was 1% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	29.00%
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	The amount has been restated to reflect current management fees.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund's benchmark is the Citigroup 3-Month Treasury Bill Index. The Fund seeks annualized returns of 5% (gross of fees) above the Citigroup 3-Month Treasury Bill Index and annualized volatility (standard deviation) of approximately 6-10%, each over a complete market cycle. The Fund does not maintain a specified interest rate duration for its portfolio. The Fund typically takes long and short positions in a range of global equity, bond, currency, and commodity markets using exchange-traded futures and forward non-U.S. exchange contracts, as well as making other investments. The Fund seeks to take advantage of GMO's proprietary investment models for global tactical asset allocation and equity, bond, currency, and commodity market selection. The Fund normally invests assets not held as margin for futures or forward transactions in cash directly (e.g., Treasury bills, Treasury floating rate notes, Treasury Separately Traded Registered Interest and Principal Securities ("STRIPS"), Federal Home Loan Bank discount notes, and other agency notes), money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds. The Fund also may invest in U.S. and non-U.S. fixed income securities of any credit quality (including below investment grade securities (commonly referred to as "junk bonds")), maturity or duration and in shares of U.S. Treasury Fund. GMO's models for this systematic process are based on the following strategies: Value-Based Strategies. Value factors compare the price of an asset class or market to an economic fundamental value. Generally, value strategies include yield analysis and mean reversion analysis. Sentiment-Based Strategies. Generally, sentiment-based strategies assess factors such as risk aversion, analyst behavior, and momentum. In implementing the Fund's investment strategy, GMO seeks to take risk positions that, in GMO's view, are proportionate to the return opportunities. As a result, during time periods when GMO believes the return opportunities are high relative to the risks involved, the Fund may take more risk relative to the Fund's benchmark. Conversely, during time periods when GMO believes the return opportunities are low relative to the risks involved, the Fund may take less risk (or no risk) relative to the Fund's benchmark. GMO may eliminate strategies or add new strategies in response to additional research, changing market conditions, or other factors. The factors GMO considers and investment methods GMO uses can change over time. The Fund may gain exposure to commodities and some other asset classes by investing through a wholly-owned subsidiary advised by GMO, which does not receive any additional management or other fees for its services. The subsidiary invests primarily in commodity-related derivatives and fixed income securities but also may gain exposure to any other investment in which the Fund is permitted to invest directly. References in this Prospectus to the Fund may refer to actions undertaken by the subsidiary as well as the Fund. The Fund does not invest directly in commodities and commodity-related derivatives, but may do so indirectly through its subsidiary (or otherwise). The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. An investment in the Fund is subject to different risks, and greater overall risk, than an investment in the components of the Fund’s benchmark. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in its wholly-owned subsidiary and in underlying funds. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in its wholly-owned subsidiary and in underlying funds, see “Description of Principal Risks.” Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results (including the annualized volatility and the annualized returns above the Citigroup 3-Month Treasury Bill Index that the Fund seeks). In addition, the Fund could produce results consistent with annualized volatility over a complete market cycle yet experience shorter periods of significantly higher or lower volatility. GMO often uses quantitative models as part of its investment process, and relies heavily on those models in making investment decisions for the Fund. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner. Futures Contracts Risk – The risk of loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile and the use of futures contracts may increase the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time and the Fund might be unable to effect closing transactions to terminate its exposure to the contract. If the Fund uses futures contracts for hedging purposes, it runs the risk of imperfect correlation between changes in the prices of the contracts and changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are the subject of the hedge. In addition, the Fund may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts may be less liquid and more volatile than U.S. contracts. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Leveraging Risk – The use of reverse repurchase agreements and other derivatives creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of its investment in its wholly-owned subsidiary and the underlying funds in which it invests, including the risk that its wholly-owned subsidiary and those underlying funds will not perform as expected. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index and a composite index computed by GMO. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance. Prior to October 3, 2011, the Fund was managed pursuant to a materially different investment strategy and would have achieved materially different performance results under its current investment strategy from that shown for periods prior to October 3, 2011.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's annual total returns from year to year for the periods indicated and by comparing the Fund's average annual total returns for different calendar periods with those of a broad-based index and a composite index computed by GMO.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 12.14% (4Q2010) Lowest Quarter: – 22.27% (4Q2008) Year-to-Date (as of 3/31/16): 0.55%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO SGM Major Markets Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.85%	[1],[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.04%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.04%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.03%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.01%	[3]
1 Year	rr_ExpenseExampleYear01	$ 103
3 Years	rr_ExpenseExampleYear03	337
5 Years	rr_ExpenseExampleYear05	589
10 Years	rr_ExpenseExampleYear10	1,311
1 Year	rr_ExpenseExampleNoRedemptionYear01	103
3 Years	rr_ExpenseExampleNoRedemptionYear03	337
5 Years	rr_ExpenseExampleNoRedemptionYear05	589
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,311
2006	rr_AnnualReturn2006	2.69%
2007	rr_AnnualReturn2007	8.58%
2008	rr_AnnualReturn2008	(26.28%)
2009	rr_AnnualReturn2009	23.95%
2010	rr_AnnualReturn2010	15.63%
2011	rr_AnnualReturn2011	(5.66%)
2012	rr_AnnualReturn2012	(1.00%)
2013	rr_AnnualReturn2013	6.16%
2014	rr_AnnualReturn2014	3.66%
2015	rr_AnnualReturn2015	0.37%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.55%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2010
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	12.14%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.27%)
1 Year	rr_AverageAnnualReturnYear01	0.37%
5 Years	rr_AverageAnnualReturnYear05	0.62%
10 Years	rr_AverageAnnualReturnYear10	1.97%
Incept.	rr_AverageAnnualReturnSinceInception	2.61%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 11, 2005
GMO SGM Major Markets Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.85%	[1],[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.04%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.99%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.03%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.96%	[3]
1 Year	rr_ExpenseExampleYear01	$ 98
3 Years	rr_ExpenseExampleYear03	321
5 Years	rr_ExpenseExampleYear05	562
10 Years	rr_ExpenseExampleYear10	1,253
1 Year	rr_ExpenseExampleNoRedemptionYear01	98
3 Years	rr_ExpenseExampleNoRedemptionYear03	321
5 Years	rr_ExpenseExampleNoRedemptionYear05	562
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,253
GMO SGM Major Markets Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.85%	[1],[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.04%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.95%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.03%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.92%	[3]
1 Year	rr_ExpenseExampleYear01	$ 94
3 Years	rr_ExpenseExampleYear03	308
5 Years	rr_ExpenseExampleYear05	540
10 Years	rr_ExpenseExampleYear10	1,207
1 Year	rr_ExpenseExampleNoRedemptionYear01	94
3 Years	rr_ExpenseExampleNoRedemptionYear03	308
5 Years	rr_ExpenseExampleNoRedemptionYear05	540
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,207
GMO SGM Major Markets Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.37%	[4]
5 Years	rr_AverageAnnualReturnYear05	0.62%	[4]
10 Years	rr_AverageAnnualReturnYear10	1.97%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	2.61%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 11, 2005	[4]
GMO SGM Major Markets Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.21%	[4]
5 Years	rr_AverageAnnualReturnYear05	0.48%	[4]
10 Years	rr_AverageAnnualReturnYear10	1.53%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	2.05%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 11, 2005	[4]
GMO SGM Major Markets Fund | Citigroup 3-Month Treasury Bill Index (Fund benchmark) (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.03%
5 Years	rr_AverageAnnualReturnYear05	0.05%
10 Years	rr_AverageAnnualReturnYear10	1.17%
Incept.	rr_AverageAnnualReturnSinceInception	1.31%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 11, 2005
GMO SGM Major Markets Fund | Citigroup 3-Month Treasury Bill Index +++ (Composite Index)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.03%
5 Years	rr_AverageAnnualReturnYear05	(1.30%)
10 Years	rr_AverageAnnualReturnYear10	0.76%
Incept.	rr_AverageAnnualReturnSinceInception	1.36%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 11, 2005

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero as a result of this waiver. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] The amount has been restated to reflect current management fees.

[3] after expense reimbursement/waiver

[4] After-tax returns do not reflect distributions made by the Fund for all periods prior to December 1, 2015, the date on which the Fund elected to change its U.S. federal income tax status from that of a partnership to a corporation. Further, as described in "Distributions and Taxes," the Fund intends to elect to be treated and to qualify and be treated each year as a regulated investment company under Subchapter M of the Internal Revenue Code of 1986, as amended, for U.S. federal income tax purposes.

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GMO Global Equity Allocation Fund

GMO GLOBAL EQUITY ALLOCATION FUND

Investment objective

Total return greater than that of its benchmark, the MSCI ACWI.

Fees and expenses

The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees	GMO Global Equity Allocation Fund Class III
Purchase premium (as a percentage of amount invested)	0.18%
Redemption fee (as a percentage of amount redeemed)	0.18%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Global Equity Allocation Fund Class III
Management fee	none
Shareholder service fee	none
Other expenses	0.01%
Acquired fund fees and expenses (underlying fund expenses)	0.64%	[1]
Total annual fund operating expenses	0.65%
Expense reimbursement	(0.01%)	[2]
Total annual fund operating expenses	0.64%	[3]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Global Equity Allocation Fund | Class III | USD ($)	102	252	414	887

If you do not sell your shares

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Global Equity Allocation Fund | Class III | USD ($)	83	231	392	859

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 15% of the average value of its portfolio.

Principal investment strategies

The Fund is a fund of funds and invests primarily in equities traded in U.S. and non-U.S. markets (including emerging markets) through shares of the Equity Funds, Alpha Only Fund and Risk Premium Fund (collectively, the "underlying GMO Funds") (see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Asset Allocation Funds"). The Fund also may invest directly in securities (including other underlying funds) and derivatives.

GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund's allocations to particular underlying GMO Funds. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund's holdings of the underlying GMO Funds in response to changes in GMO's investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund's investments. The factors GMO considers and investment methods GMO uses can change over time.

Under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities (see "Name Policies"). The term "equities" refers to direct and indirect (e.g., through the underlying GMO Funds) investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts.

The Fund may invest in securities of companies of any market capitalization.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund’s benchmark (which is a broad-based index) and a composite index computed by GMO. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 16.20% (2Q2009)
Lowest Quarter: – 15.65% (4Q2008)
Year-to-Date (as of 3/31/16): 1.86%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Global Equity Allocation Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(6.17%)	4.82%	4.00%	7.40%	Nov. 26, 1996
Class III | Return After Taxes on Distributions	(8.43%)	3.07%	2.30%	5.23%	Nov. 26, 1996
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(1.14%)	4.04%	3.37%	5.69%	Nov. 26, 1996
MSCI ACWI (Fund benchmark) (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(2.36%)	6.09%	4.76%	5.48%	Nov. 26, 1996
MSCI ACWI + (Composite index)	(2.36%)	6.09%	4.15%	5.56%	Nov. 26, 1996

[1] These indirect expenses include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.59% and 0.05%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Global Equity Allocation Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO GLOBAL EQUITY ALLOCATION FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return greater than that of its benchmark, the MSCI ACWI.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 15% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	15.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund is a fund of funds and invests primarily in equities traded in U.S. and non-U.S. markets (including emerging markets) through shares of the Equity Funds, Alpha Only Fund and Risk Premium Fund (collectively, the "underlying GMO Funds") (see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Asset Allocation Funds"). The Fund also may invest directly in securities (including other underlying funds) and derivatives. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund's allocations to particular underlying GMO Funds. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund's holdings of the underlying GMO Funds in response to changes in GMO's investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund's investments. The factors GMO considers and investment methods GMO uses can change over time. Under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities (see "Name Policies"). The term "equities" refers to direct and indirect (e.g., through the underlying GMO Funds) investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The Fund may invest in securities of companies of any market capitalization. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund’s benchmark (which is a broad-based index) and a composite index computed by GMO. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's annual total returns from year to year for the periods indicated and by comparing the Fund's average annual total returns for different calendar periods with those of the Fund's benchmark (which is a broad-based index) and a composite index computed by GMO.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 16.20% (2Q2009) Lowest Quarter: – 15.65% (4Q2008) Year-to-Date (as of 3/31/16): 1.86%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Global Equity Allocation Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.18%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.18%
Management fee	rr_ManagementFeesOverAssets	none
Distribution or Similar (Non 12b-1) Fees	rr_DistributionOrSimilarNon12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.01%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.64%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.65%
Expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.64%	[3]
1 Year	rr_ExpenseExampleYear01	$ 102
3 Years	rr_ExpenseExampleYear03	252
5 Years	rr_ExpenseExampleYear05	414
10 Years	rr_ExpenseExampleYear10	887
1 Year	rr_ExpenseExampleNoRedemptionYear01	83
3 Years	rr_ExpenseExampleNoRedemptionYear03	231
5 Years	rr_ExpenseExampleNoRedemptionYear05	392
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 859
2006	rr_AnnualReturn2006	16.57%
2007	rr_AnnualReturn2007	9.57%
2008	rr_AnnualReturn2008	(33.09%)
2009	rr_AnnualReturn2009	24.50%
2010	rr_AnnualReturn2010	9.98%
2011	rr_AnnualReturn2011	(1.95%)
2012	rr_AnnualReturn2012	14.69%
2013	rr_AnnualReturn2013	20.97%
2014	rr_AnnualReturn2014	(0.88%)
2015	rr_AnnualReturn2015	(5.83%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	1.86%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	16.20%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(15.65%)
1 Year	rr_AverageAnnualReturnYear01	(6.17%)
5 Years	rr_AverageAnnualReturnYear05	4.82%
10 Years	rr_AverageAnnualReturnYear10	4.00%
Incept.	rr_AverageAnnualReturnSinceInception	7.40%
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 26, 1996
GMO Global Equity Allocation Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(8.43%)
5 Years	rr_AverageAnnualReturnYear05	3.07%
10 Years	rr_AverageAnnualReturnYear10	2.30%
Incept.	rr_AverageAnnualReturnSinceInception	5.23%
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 26, 1996
GMO Global Equity Allocation Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(1.14%)
5 Years	rr_AverageAnnualReturnYear05	4.04%
10 Years	rr_AverageAnnualReturnYear10	3.37%
Incept.	rr_AverageAnnualReturnSinceInception	5.69%
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 26, 1996
GMO Global Equity Allocation Fund | MSCI ACWI (Fund benchmark) (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.36%)
5 Years	rr_AverageAnnualReturnYear05	6.09%
10 Years	rr_AverageAnnualReturnYear10	4.76%
Incept.	rr_AverageAnnualReturnSinceInception	5.48%
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 26, 1996
GMO Global Equity Allocation Fund | MSCI ACWI + (Composite index)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.36%)
5 Years	rr_AverageAnnualReturnYear05	6.09%
10 Years	rr_AverageAnnualReturnYear10	4.15%
Incept.	rr_AverageAnnualReturnSinceInception	5.56%
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 26, 1996

[1] These indirect expenses include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.59% and 0.05%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

XML

GMO Global Developed Equity Allocation Fund

GMO GLOBAL DEVELOPED EQUITY ALLOCATION FUND

Investment objective

Total return greater than that of its benchmark, the MSCI World Index.

Fees and expenses

The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees	GMO Global Developed Equity Allocation Fund Class III
Purchase premium (as a percentage of amount invested)	0.08%
Redemption fee (as a percentage of amount redeemed)	0.08%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Global Developed Equity Allocation Fund Class III
Management fee	none
Shareholder service fee	none
Other expenses	0.01%
Acquired fund fees and expenses (underlying fund expenses)	0.55%	[1]
Total annual fund operating expenses	0.56%
Expense reimbursement	(0.01%)	[2]
Total annual fund operating expenses	0.55%	[3]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Global Developed Equity Allocation Fund | Class III | USD ($)	73	202	343	754

If you do not sell your shares

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Global Developed Equity Allocation Fund | Class III | USD ($)	64	193	333	741

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 14% of the average value of its portfolio.

Principal investment strategies

The Fund is a fund of funds and invests primarily in equities traded in U.S. and non-U.S. markets (including emerging markets) through shares of the Equity Funds, Alpha Only Fund, and Risk Premium Fund (collectively, the “underlying GMO Funds”) (see “Additional Information About the Funds’ Investment Strategies, Risks, and Expenses — Asset Allocation Funds”). The Fund also may invest directly in securities (including other underlying funds) and derivatives.

GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund’s allocations to particular underlying GMO Funds. An important component of those forecasts is GMO’s expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund’s holdings of the underlying GMO Funds in response to changes in GMO’s investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund’s investments. The factors GMO considers and investment methods GMO uses can change over time.

Under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities (see “Name Policies”). In addition, under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities tied economically to developed markets (see “Name Policies”). The Fund also may invest in equities in emerging markets, but those investments typically will represent 10% or less of the Fund’s net assets measured at the time of purchase. The term “equities” refers to direct and indirect (e.g., through the underlying GMO Funds) investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The term “developed markets” means those countries included in the MSCI World Index, a global developed markets equity index, and countries with similar characteristics (e.g., countries that have sustained economic development, sufficient liquidity for listed companies and accessible markets).

The Fund may invest in securities of companies of any market capitalization.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 14.41% (3Q2010)
Lowest Quarter: – 15.27% (4Q2008)
Year-to-Date (as of 3/31/16): 0.81%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Global Developed Equity Allocation Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(4.38%)	6.51%	4.87%	5.59%	Jun. 16, 2005
Class III | Return After Taxes on Distributions	(6.67%)	5.12%	3.61%	4.32%	Jun. 16, 2005
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(0.10%)	5.33%	4.00%	4.59%	Jun. 16, 2005
MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.87%)	7.59%	4.98%	5.62%	Jun. 16, 2005

[1] These indirect expenses include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.53% and 0.02%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Global Developed Equity Allocation Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO GLOBAL DEVELOPED EQUITY ALLOCATION FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return greater than that of its benchmark, the MSCI World Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 14% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	14.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund is a fund of funds and invests primarily in equities traded in U.S. and non-U.S. markets (including emerging markets) through shares of the Equity Funds, Alpha Only Fund, and Risk Premium Fund (collectively, the “underlying GMO Funds”) (see “Additional Information About the Funds’ Investment Strategies, Risks, and Expenses — Asset Allocation Funds”). The Fund also may invest directly in securities (including other underlying funds) and derivatives. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund’s allocations to particular underlying GMO Funds. An important component of those forecasts is GMO’s expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund’s holdings of the underlying GMO Funds in response to changes in GMO’s investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund’s investments. The factors GMO considers and investment methods GMO uses can change over time. Under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities (see “Name Policies”). In addition, under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities tied economically to developed markets (see “Name Policies”). The Fund also may invest in equities in emerging markets, but those investments typically will represent 10% or less of the Fund’s net assets measured at the time of purchase. The term “equities” refers to direct and indirect (e.g., through the underlying GMO Funds) investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The term “developed markets” means those countries included in the MSCI World Index, a global developed markets equity index, and countries with similar characteristics (e.g., countries that have sustained economic development, sufficient liquidity for listed companies and accessible markets). The Fund may invest in securities of companies of any market capitalization. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 14.41% (3Q2010) Lowest Quarter: – 15.27% (4Q2008) Year-to-Date (as of 3/31/16): 0.81%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Global Developed Equity Allocation Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.08%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.08%
Management fee	rr_ManagementFeesOverAssets	none
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.01%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.55%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.56%
Expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.55%	[3]
1 Year	rr_ExpenseExampleYear01	$ 73
3 Years	rr_ExpenseExampleYear03	202
5 Years	rr_ExpenseExampleYear05	343
10 Years	rr_ExpenseExampleYear10	754
1 Year	rr_ExpenseExampleNoRedemptionYear01	64
3 Years	rr_ExpenseExampleNoRedemptionYear03	193
5 Years	rr_ExpenseExampleNoRedemptionYear05	333
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 741
2006	rr_AnnualReturn2006	20.09%
2007	rr_AnnualReturn2007	10.03%
2008	rr_AnnualReturn2008	(32.08%)
2009	rr_AnnualReturn2009	19.93%
2010	rr_AnnualReturn2010	9.00%
2011	rr_AnnualReturn2011	0.26%
2012	rr_AnnualReturn2012	14.61%
2013	rr_AnnualReturn2013	25.34%
2014	rr_AnnualReturn2014	(0.46%)
2015	rr_AnnualReturn2015	(4.22%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.81%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2010
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	14.41%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(15.27%)
1 Year	rr_AverageAnnualReturnYear01	(4.38%)
5 Years	rr_AverageAnnualReturnYear05	6.51%
10 Years	rr_AverageAnnualReturnYear10	4.87%
Incept.	rr_AverageAnnualReturnSinceInception	5.59%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 16, 2005
GMO Global Developed Equity Allocation Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(6.67%)
5 Years	rr_AverageAnnualReturnYear05	5.12%
10 Years	rr_AverageAnnualReturnYear10	3.61%
Incept.	rr_AverageAnnualReturnSinceInception	4.32%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 16, 2005
GMO Global Developed Equity Allocation Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.10%)
5 Years	rr_AverageAnnualReturnYear05	5.33%
10 Years	rr_AverageAnnualReturnYear10	4.00%
Incept.	rr_AverageAnnualReturnSinceInception	4.59%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 16, 2005
GMO Global Developed Equity Allocation Fund | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.87%)
5 Years	rr_AverageAnnualReturnYear05	7.59%
10 Years	rr_AverageAnnualReturnYear10	4.98%
Incept.	rr_AverageAnnualReturnSinceInception	5.62%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 16, 2005

[1] These indirect expenses include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.53% and 0.02%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

XML

GMO Developed World Stock Fund

GMO DEVELOPED WORLD STOCK FUND

Investment objective

High total return.

Fees and expenses

The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees - GMO Developed World Stock Fund		Class III	Class IV
Purchase premium (as a percentage of amount invested)	[1]	0.25%	0.25%
Redemption fee (as a percentage of amount redeemed)	[1]	0.25%	0.25%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Developed World Stock Fund		Class III	Class IV
Management fee	[1]	0.45%	0.45%
Shareholder service fee	[1]	0.15%	0.10%
Other expenses		0.16%	0.16%
Total annual fund operating expenses		0.76%	0.71%
Expense reimbursement/waiver	[1]	(0.15%)	(0.15%)
Total annual fund operating expenses	[2]	0.61%	0.56%

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example - GMO Developed World Stock Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	113	281	462	989
Class IV	108	265	435	929

If you do not sell your shares

Expense Example, No Redemption - GMO Developed World Stock Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	87	252	432	951
Class IV	82	236	404	891

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 99% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 79% of the average value of its portfolio.

Principal investment strategies

GMO seeks to achieve the Fund's investment objective by investing primarily in a portfolio of stocks in global developed equity markets. GMO selects the stocks the Fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, the overall global economy, and governmental policies.

In selecting stocks for the Fund, GMO uses a combination of investment methods to identify stocks that GMO believes have positive return potential relative to other stocks in global developed equity markets. Some of these methods evaluate individual stocks or groups of stocks based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a stock or groups of stocks relative to global developed equity markets. GMO also uses its multi-year return forecasts for asset classes and other groups of securities in its investment process and may adjust the Fund's portfolio based on factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, region, or currency. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark.

As an alternative to investing directly in stocks, the Fund may invest in other GMO Funds (collectively, the "underlying GMO Funds"), exchange-traded and over-the-counter (OTC) derivatives, and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, forward currency contracts, and swap contracts. In addition, the Fund may lend its portfolio securities.

Under normal circumstances, the Fund invests directly and indirectly (e.g., through underlying funds or derivatives) at least 80% of its assets in stocks tied economically to developed markets (see "Name Policies"). For this purpose, the term "stocks" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts, and the term "developed markets" refers to those countries included in the MSCI World Index, a global developed markets equity index, and countries with similar characteristics (e.g., countries that have sustained economic development, sufficient liquidity for listed companies and accessible markets).

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund and some of the underlying GMO Funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund or those underlying GMO Funds may affect the Fund’s or underlying GMO Funds’ performance more than if the Fund or those underlying GMO Funds were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 18.37% (2Q2009)
Lowest Quarter: – 19.92% (4Q2008)
Year-to-Date (as of 3/31/16): – 1.06%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Developed World Stock Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(2.29%)	6.90%	4.36%	4.71%	Aug. 01, 2005
Class III | Return After Taxes on Distributions	(3.87%)	6.12%	3.50%	3.88%	Aug. 01, 2005
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(0.21%)	5.41%	3.44%	3.74%	Aug. 01, 2005
Class III | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.87%)	7.59%	4.98%	5.38%	Aug. 01, 2005
Class IV	(2.26%)	6.95%	4.41%	4.69%	Sep. 01, 2005
Class IV | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.87%)	7.59%	4.98%	5.29%	Sep. 01, 2005

[1] An additional purchase premium and redemption fee of 0.005% is charged for any purchases/redemptions (or any portion of a purchase/redemption) effected in a currency other than the U.S. dollar.

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Developed World Stock Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO DEVELOPED WORLD STOCK FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	High total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 99% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 79% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	99.00%
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO seeks to achieve the Fund's investment objective by investing primarily in a portfolio of stocks in global developed equity markets. GMO selects the stocks the Fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, the overall global economy, and governmental policies. In selecting stocks for the Fund, GMO uses a combination of investment methods to identify stocks that GMO believes have positive return potential relative to other stocks in global developed equity markets. Some of these methods evaluate individual stocks or groups of stocks based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a stock or groups of stocks relative to global developed equity markets. GMO also uses its multi-year return forecasts for asset classes and other groups of securities in its investment process and may adjust the Fund's portfolio based on factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, region, or currency. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. As an alternative to investing directly in stocks, the Fund may invest in other GMO Funds (collectively, the "underlying GMO Funds"), exchange-traded and over-the-counter (OTC) derivatives, and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, forward currency contracts, and swap contracts. In addition, the Fund may lend its portfolio securities. Under normal circumstances, the Fund invests directly and indirectly (e.g., through underlying funds or derivatives) at least 80% of its assets in stocks tied economically to developed markets (see "Name Policies"). For this purpose, the term "stocks" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts, and the term "developed markets" refers to those countries included in the MSCI World Index, a global developed markets equity index, and countries with similar characteristics (e.g., countries that have sustained economic development, sufficient liquidity for listed companies and accessible markets). The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund and some of the underlying GMO Funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund or those underlying GMO Funds may affect the Fund’s or underlying GMO Funds’ performance more than if the Fund or those underlying GMO Funds were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund and some of the underlying GMO Funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund or those underlying GMO Funds may affect the Fund’s or underlying GMO Funds’ performance more than if the Fund or those underlying GMO Funds were diversified investment companies.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 18.37% (2Q2009) Lowest Quarter: – 19.92% (4Q2008) Year-to-Date (as of 3/31/16): – 1.06%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Developed World Stock Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.25%	[1]
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.25%	[1]
Management fee	rr_ManagementFeesOverAssets	0.45%	[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.16%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.76%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.15%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.61%	[3]
1 Year	rr_ExpenseExampleYear01	$ 113
3 Years	rr_ExpenseExampleYear03	281
5 Years	rr_ExpenseExampleYear05	462
10 Years	rr_ExpenseExampleYear10	989
1 Year	rr_ExpenseExampleNoRedemptionYear01	87
3 Years	rr_ExpenseExampleNoRedemptionYear03	252
5 Years	rr_ExpenseExampleNoRedemptionYear05	432
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 951
2006	rr_AnnualReturn2006	20.98%
2007	rr_AnnualReturn2007	7.24%
2008	rr_AnnualReturn2008	(37.58%)
2009	rr_AnnualReturn2009	22.79%
2010	rr_AnnualReturn2010	10.37%
2011	rr_AnnualReturn2011	(3.27%)
2012	rr_AnnualReturn2012	12.92%
2013	rr_AnnualReturn2013	29.21%
2014	rr_AnnualReturn2014	1.25%
2015	rr_AnnualReturn2015	(1.80%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(1.06%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	18.37%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(19.92%)
1 Year	rr_AverageAnnualReturnYear01	(2.29%)
5 Years	rr_AverageAnnualReturnYear05	6.90%
10 Years	rr_AverageAnnualReturnYear10	4.36%
Incept.	rr_AverageAnnualReturnSinceInception	4.71%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 01, 2005
GMO Developed World Stock Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.25%	[1]
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.25%	[1]
Management fee	rr_ManagementFeesOverAssets	0.45%	[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.16%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.71%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.15%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.56%	[3]
1 Year	rr_ExpenseExampleYear01	$ 108
3 Years	rr_ExpenseExampleYear03	265
5 Years	rr_ExpenseExampleYear05	435
10 Years	rr_ExpenseExampleYear10	929
1 Year	rr_ExpenseExampleNoRedemptionYear01	82
3 Years	rr_ExpenseExampleNoRedemptionYear03	236
5 Years	rr_ExpenseExampleNoRedemptionYear05	404
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 891
1 Year	rr_AverageAnnualReturnYear01	(2.26%)
5 Years	rr_AverageAnnualReturnYear05	6.95%
10 Years	rr_AverageAnnualReturnYear10	4.41%
Incept.	rr_AverageAnnualReturnSinceInception	4.69%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 2005
GMO Developed World Stock Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(3.87%)
5 Years	rr_AverageAnnualReturnYear05	6.12%
10 Years	rr_AverageAnnualReturnYear10	3.50%
Incept.	rr_AverageAnnualReturnSinceInception	3.88%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 01, 2005
GMO Developed World Stock Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.21%)
5 Years	rr_AverageAnnualReturnYear05	5.41%
10 Years	rr_AverageAnnualReturnYear10	3.44%
Incept.	rr_AverageAnnualReturnSinceInception	3.74%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 01, 2005
GMO Developed World Stock Fund | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.87%)
5 Years	rr_AverageAnnualReturnYear05	7.59%
10 Years	rr_AverageAnnualReturnYear10	4.98%
Incept.	rr_AverageAnnualReturnSinceInception	5.38%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 01, 2005
GMO Developed World Stock Fund | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.87%)
5 Years	rr_AverageAnnualReturnYear05	7.59%
10 Years	rr_AverageAnnualReturnYear10	4.98%
Incept.	rr_AverageAnnualReturnSinceInception	5.29%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 2005

[1] An additional purchase premium and redemption fee of 0.005% is charged for any purchases/redemptions (or any portion of a purchase/redemption) effected in a currency other than the U.S. dollar.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement/waiver

XML

GMO Quality Fund

GMO QUALITY FUND

Investment objective

Total return.

Fees and expenses

The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Quality Fund		Class III	Class IV	Class V	Class VI
Management fee	[1]	0.33%	0.33%	0.33%	0.33%
Shareholder service fee	[1]	0.15%	0.105%	0.085%	0.055%
Other expenses		0.02%	0.02%	0.02%	0.02%
Total annual fund operating expenses		0.50%	0.46%	0.44%	0.41%
Expense reimbursement/waiver	[1]	(0.02%)	(0.02%)	(0.02%)	(0.02%)
Total annual fund operating expenses	[2]	0.48%	0.44%	0.42%	0.39%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - GMO Quality Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	49	158	278	626
Class IV	45	146	256	577
Class V	43	139	244	553
Class VI	40	130	228	516

Expense Example, No Redemption - GMO Quality Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	49	158	278	626
Class IV	45	146	256	577
Class V	43	139	244	553
Class VI	40	130	228	516

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 37% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 17% of the average value of its portfolio.

Principal investment strategies

GMO seeks to achieve the Fund's investment objective by investing primarily in equities of companies that GMO believes to be of high quality. A high quality company is generally one that GMO believes has an established business that will deliver a high level of return on past investments and that will utilize cash flows in the future by making investments with potential for high levels of return on capital or by returning cash to shareholders through dividends, share buybacks, or other mechanisms.

In selecting securities for the Fund, GMO uses a combination of investment methods and may consider both quantitative factors, based on profitability, profit stability, leverage, and other publicly available financial information, and fundamental factors, based on an assessment of future profitability, capital allocation, sustainability against competitive forces, and growth opportunities. GMO may also rely on valuation methodologies, such as discounted cash flow analysis, forecasted financial information, and patterns of information, such as price movement or volatility of a security or groups of securities.

The Fund is permitted to invest directly and indirectly (e.g., through underlying funds or derivatives) in equities of companies tied economically to any country in the world, including emerging countries. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts.

At times, the Fund may have substantial exposure to a single industry, sector, country, region, or currency. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark.

As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, forward currency contracts, and swap contracts. In addition, the Fund may lend its portfolio securities.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. The Fund invests in the securities of a limited number of issuers, and a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund invested in the securities of a larger number of issuers.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 11.53% (3Q2010)
Lowest Quarter: – 13.13% (4Q2008)
Year-to-Date (as of 3/31/16): 4.14%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Quality Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	1.50%	12.37%	7.47%	6.43%	Feb. 06, 2004
Class III | Return After Taxes on Distributions	(2.35%)	9.31%	5.82%	5.02%	Feb. 06, 2004
Class III | Return After Taxes on Distributions and Sale of Fund Shares	3.67%	9.72%	6.00%	5.18%	Feb. 06, 2004
Class III | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)	1.38%	12.57%	7.31%	7.20%	Feb. 06, 2004
Class IV	1.51%	12.43%	7.50%	6.47%	Feb. 06, 2004
Class IV | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)	1.38%	12.57%	7.31%	7.20%	Feb. 06, 2004
Class V	1.60%	12.46%		7.05%	Dec. 08, 2006
Class V | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)	1.38%	12.57%		6.44%	Dec. 08, 2006
Class VI	1.57%	12.48%		7.08%	Dec. 08, 2006
Class VI | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)	1.38%	12.57%		6.44%	Dec. 08, 2006

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Quality Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO QUALITY FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 37% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 17% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	37.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO seeks to achieve the Fund's investment objective by investing primarily in equities of companies that GMO believes to be of high quality. A high quality company is generally one that GMO believes has an established business that will deliver a high level of return on past investments and that will utilize cash flows in the future by making investments with potential for high levels of return on capital or by returning cash to shareholders through dividends, share buybacks, or other mechanisms. In selecting securities for the Fund, GMO uses a combination of investment methods and may consider both quantitative factors, based on profitability, profit stability, leverage, and other publicly available financial information, and fundamental factors, based on an assessment of future profitability, capital allocation, sustainability against competitive forces, and growth opportunities. GMO may also rely on valuation methodologies, such as discounted cash flow analysis, forecasted financial information, and patterns of information, such as price movement or volatility of a security or groups of securities. The Fund is permitted to invest directly and indirectly (e.g., through underlying funds or derivatives) in equities of companies tied economically to any country in the world, including emerging countries. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. At times, the Fund may have substantial exposure to a single industry, sector, country, region, or currency. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, forward currency contracts, and swap contracts. In addition, the Fund may lend its portfolio securities. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. The Fund invests in the securities of a limited number of issuers, and a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund invested in the securities of a larger number of issuers. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 11.53% (3Q2010) Lowest Quarter: – 13.13% (4Q2008) Year-to-Date (as of 3/31/16): 4.14%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Quality Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.33%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.50%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.48%	[2]
1 Year	rr_ExpenseExampleYear01	$ 49
3 Years	rr_ExpenseExampleYear03	158
5 Years	rr_ExpenseExampleYear05	278
10 Years	rr_ExpenseExampleYear10	626
1 Year	rr_ExpenseExampleNoRedemptionYear01	49
3 Years	rr_ExpenseExampleNoRedemptionYear03	158
5 Years	rr_ExpenseExampleNoRedemptionYear05	278
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 626
2006	rr_AnnualReturn2006	12.74%
2007	rr_AnnualReturn2007	6.01%
2008	rr_AnnualReturn2008	(24.12%)
2009	rr_AnnualReturn2009	19.85%
2010	rr_AnnualReturn2010	5.47%
2011	rr_AnnualReturn2011	11.75%
2012	rr_AnnualReturn2012	12.00%
2013	rr_AnnualReturn2013	25.36%
2014	rr_AnnualReturn2014	12.50%
2015	rr_AnnualReturn2015	1.50%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	4.14%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2010
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	11.53%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(13.13%)
1 Year	rr_AverageAnnualReturnYear01	1.50%
5 Years	rr_AverageAnnualReturnYear05	12.37%
10 Years	rr_AverageAnnualReturnYear10	7.47%
Incept.	rr_AverageAnnualReturnSinceInception	6.43%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 06, 2004
GMO Quality Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.33%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.105%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.46%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.44%	[2]
1 Year	rr_ExpenseExampleYear01	$ 45
3 Years	rr_ExpenseExampleYear03	146
5 Years	rr_ExpenseExampleYear05	256
10 Years	rr_ExpenseExampleYear10	577
1 Year	rr_ExpenseExampleNoRedemptionYear01	45
3 Years	rr_ExpenseExampleNoRedemptionYear03	146
5 Years	rr_ExpenseExampleNoRedemptionYear05	256
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 577
1 Year	rr_AverageAnnualReturnYear01	1.51%
5 Years	rr_AverageAnnualReturnYear05	12.43%
10 Years	rr_AverageAnnualReturnYear10	7.50%
Incept.	rr_AverageAnnualReturnSinceInception	6.47%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 06, 2004
GMO Quality Fund | Class V
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.33%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.085%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.44%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.42%	[2]
1 Year	rr_ExpenseExampleYear01	$ 43
3 Years	rr_ExpenseExampleYear03	139
5 Years	rr_ExpenseExampleYear05	244
10 Years	rr_ExpenseExampleYear10	553
1 Year	rr_ExpenseExampleNoRedemptionYear01	43
3 Years	rr_ExpenseExampleNoRedemptionYear03	139
5 Years	rr_ExpenseExampleNoRedemptionYear05	244
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 553
1 Year	rr_AverageAnnualReturnYear01	1.60%
5 Years	rr_AverageAnnualReturnYear05	12.46%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	7.05%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 08, 2006
GMO Quality Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.33%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.41%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.39%	[2]
1 Year	rr_ExpenseExampleYear01	$ 40
3 Years	rr_ExpenseExampleYear03	130
5 Years	rr_ExpenseExampleYear05	228
10 Years	rr_ExpenseExampleYear10	516
1 Year	rr_ExpenseExampleNoRedemptionYear01	40
3 Years	rr_ExpenseExampleNoRedemptionYear03	130
5 Years	rr_ExpenseExampleNoRedemptionYear05	228
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 516
1 Year	rr_AverageAnnualReturnYear01	1.57%
5 Years	rr_AverageAnnualReturnYear05	12.48%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	7.08%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 08, 2006
GMO Quality Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.35%)
5 Years	rr_AverageAnnualReturnYear05	9.31%
10 Years	rr_AverageAnnualReturnYear10	5.82%
Incept.	rr_AverageAnnualReturnSinceInception	5.02%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 06, 2004
GMO Quality Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	3.67%
5 Years	rr_AverageAnnualReturnYear05	9.72%
10 Years	rr_AverageAnnualReturnYear10	6.00%
Incept.	rr_AverageAnnualReturnSinceInception	5.18%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 06, 2004
GMO Quality Fund | S&P 500 Index (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.38%
5 Years	rr_AverageAnnualReturnYear05	12.57%
10 Years	rr_AverageAnnualReturnYear10	7.31%
Incept.	rr_AverageAnnualReturnSinceInception	7.20%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 06, 2004
GMO Quality Fund | S&P 500 Index (reflects no deduction for fees, expenses, or taxes) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.38%
5 Years	rr_AverageAnnualReturnYear05	12.57%
10 Years	rr_AverageAnnualReturnYear10	7.31%
Incept.	rr_AverageAnnualReturnSinceInception	7.20%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 06, 2004
GMO Quality Fund | S&P 500 Index (reflects no deduction for fees, expenses, or taxes) | Class V
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.38%
5 Years	rr_AverageAnnualReturnYear05	12.57%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	6.44%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 08, 2006
GMO Quality Fund | S&P 500 Index (reflects no deduction for fees, expenses, or taxes) | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.38%
5 Years	rr_AverageAnnualReturnYear05	12.57%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	6.44%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 08, 2006

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

XML

GMO Resources Fund

GMO RESOURCES FUND

Investment objective

Total return.

Fees and expenses

The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees - GMO Resources Fund	Class III	Class IV	Class V	Class VI
Purchase premium (as a percentage of amount invested)	0.30%	0.30%	0.30%	0.30%
Redemption fee (as a percentage of amount redeemed)	0.30%	0.30%	0.30%	0.30%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Resources Fund		Class III	Class IV	Class V	Class VI
Management fee	[1]	0.50%	0.50%	0.50%	0.50%
Shareholder service fee	[1]	0.15%	0.10%	0.085%	0.055%
Other expenses		0.22%	0.23%	0.23%	0.23%
Total annual fund operating expenses		0.87%	0.83%	0.82%	0.79%
Expense reimbursement/waiver	[1]	(0.10%)	(0.11%)	(0.11%)	(0.11%)
Total annual fund operating expenses	[2]	0.77%	0.72%	0.71%	0.68%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example - GMO Resources Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	140	331	538	1,135
Class IV	135	317	515	1,087
Class V	133	314	510	1,075
Class VI	130	304	493	1,040

If you do not sell your shares

Expense Example, No Redemption - GMO Resources Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	108	297	501	1,090
Class IV	103	283	478	1,042
Class V	102	280	473	1,030
Class VI	99	271	457	995

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 130% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 92% of the average value of its portfolio.

Principal investment strategies

GMO seeks to achieve the Fund’s investment objective by investing primarily in securities of companies in the natural resources sector (as defined below). Given the limited supply of many natural resources and the expected growth and industrialization of countries that are not members of the Organisation for Economic Co-operation and Development (OECD), GMO believes global demand for many natural resources, and therefore prices of these natural resources generally, will increase over a long time period. In managing the Fund, GMO seeks to invest in the securities of companies that it believes will benefit from this expected long-term rise in natural resource prices.

GMO selects the securities the Fund should buy or sell based on its evaluation of companies’ published financial information and corporate behavior, securities’ prices, commodities’ prices, equity and bond markets, the overall global economy, and governmental policies.

In selecting securities for the Fund, GMO uses a combination of investment methods to identify securities that GMO believes have positive return potential relative to other securities of companies in the natural resources sector. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to other stocks in the natural resources sector. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, or region. The Fund may invest in securities of companies of any market capitalization. The Fund also may engage in merger arbitrage transactions. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund’s risk relative to, any securities index or securities benchmark.

As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, and swap contracts. In addition, the Fund may lend its portfolio securities.

The Fund has a fundamental policy to concentrate its investments in the natural resources sector, and, under normal market conditions, the Fund invests at least 80% of its assets in the securities of companies in that sector. The Fund considers the “natural resources sector” to include companies that own, produce, refine, process, transport, and market natural resources and companies that provide related equipment, infrastructure, and services. The sector includes, for example, the following industries: integrated oil, oil and gas exploration and production, gold and other precious metals, steel and iron ore production, energy services and technology, base metal production, forest products, farming products, paper products, chemicals, building materials, coal, water, alternative energy sources, and environmental services. The Fund is permitted to invest directly and indirectly (e.g., through underlying funds or derivatives) in securities of companies tied economically to any country in the world, including emerging countries. In addition to its investments in companies in the natural resources sector, the Fund also may invest up to 20% of its net assets in securities of any type of company.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Focused Investment Risk – By concentrating its investments in the natural resources sector, the Fund is particularly exposed to adverse developments, including adverse price movements, affecting issuers in that sector and is subject to greater risks than a fund that invests in a wider range of industries. In addition, the market prices of securities of companies in the natural resources sector are often more volatile than securities of companies in other industries. Some of the commodities used as raw materials or produced by these companies are subject to broad price fluctuations as a result of industry-wide supply and demand factors. Companies in the natural resources sector often have limited pricing power over supplies or for the products they sell and that can affect their profitability, and are often capital-intensive and use significant amounts of leverage. Projects in the natural resources sector may have long setup times, and companies cannot ensure that the market will be favorable at the time the project begins production. Companies in the natural resources sector also may be subject to special risks associated with natural or man-made disasters. In addition, the natural resources sector can be especially affected by events relating to international political and economic developments, government regulations, energy conservation, and the success of exploration projects. Because the Fund invests primarily in the natural resources sector, it runs the risk of performing poorly during an economic downturn or a decline in demand for natural resources.

• Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate more than if the Fund had a broader range of investments.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the MSCI ACWI Commodity Producers Index and the MSCI ACWI. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 12.84% (3Q2013)
Lowest Quarter: – 20.51% (3Q2015)
Year-to-Date (as of 3/31/16): 12.09%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Resources Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(22.49%)			(7.18%)	Dec. 28, 2011
Class III | Return After Taxes on Distributions	(22.90%)			(8.47%)	Dec. 28, 2011
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(12.07%)			(5.08%)	Dec. 28, 2011
Class III | MSCI ACWI Commodity Producers Index (Fund benchmark) (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(25.83%)			(9.33%)	Dec. 28, 2011
Class III | MSCI ACWI (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(2.36%)			10.03%	Dec. 28, 2011
Class IV	(22.44%)			(12.95%)	Mar. 20, 2013
Class IV | MSCI ACWI Commodity Producers Index (Fund benchmark) (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(25.83%)			(13.75%)	Mar. 20, 2013
Class IV | MSCI ACWI (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(2.36%)			5.97%	Mar. 20, 2013

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the portion of its "Specified Operating Expenses" (as defined below) that exceeds 0.10% of the Fund's average daily net assets. "Specified Operating Expenses" means only the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Resources Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO RESOURCES FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 130% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 92% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	130.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO seeks to achieve the Fund’s investment objective by investing primarily in securities of companies in the natural resources sector (as defined below). Given the limited supply of many natural resources and the expected growth and industrialization of countries that are not members of the Organisation for Economic Co-operation and Development (OECD), GMO believes global demand for many natural resources, and therefore prices of these natural resources generally, will increase over a long time period. In managing the Fund, GMO seeks to invest in the securities of companies that it believes will benefit from this expected long-term rise in natural resource prices. GMO selects the securities the Fund should buy or sell based on its evaluation of companies’ published financial information and corporate behavior, securities’ prices, commodities’ prices, equity and bond markets, the overall global economy, and governmental policies. In selecting securities for the Fund, GMO uses a combination of investment methods to identify securities that GMO believes have positive return potential relative to other securities of companies in the natural resources sector. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to other stocks in the natural resources sector. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, or region. The Fund may invest in securities of companies of any market capitalization. The Fund also may engage in merger arbitrage transactions. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund’s risk relative to, any securities index or securities benchmark. As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, and swap contracts. In addition, the Fund may lend its portfolio securities. The Fund has a fundamental policy to concentrate its investments in the natural resources sector, and, under normal market conditions, the Fund invests at least 80% of its assets in the securities of companies in that sector. The Fund considers the “natural resources sector” to include companies that own, produce, refine, process, transport, and market natural resources and companies that provide related equipment, infrastructure, and services. The sector includes, for example, the following industries: integrated oil, oil and gas exploration and production, gold and other precious metals, steel and iron ore production, energy services and technology, base metal production, forest products, farming products, paper products, chemicals, building materials, coal, water, alternative energy sources, and environmental services. The Fund is permitted to invest directly and indirectly (e.g., through underlying funds or derivatives) in securities of companies tied economically to any country in the world, including emerging countries. In addition to its investments in companies in the natural resources sector, the Fund also may invest up to 20% of its net assets in securities of any type of company. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	The Fund has a fundamental policy to concentrate its investments in the natural resources sector, and, under normal market conditions, the Fund invests at least 80% of its assets in the securities of companies in that sector.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Focused Investment Risk – By concentrating its investments in the natural resources sector, the Fund is particularly exposed to adverse developments, including adverse price movements, affecting issuers in that sector and is subject to greater risks than a fund that invests in a wider range of industries. In addition, the market prices of securities of companies in the natural resources sector are often more volatile than securities of companies in other industries. Some of the commodities used as raw materials or produced by these companies are subject to broad price fluctuations as a result of industry-wide supply and demand factors. Companies in the natural resources sector often have limited pricing power over supplies or for the products they sell and that can affect their profitability, and are often capital-intensive and use significant amounts of leverage. Projects in the natural resources sector may have long setup times, and companies cannot ensure that the market will be favorable at the time the project begins production. Companies in the natural resources sector also may be subject to special risks associated with natural or man-made disasters. In addition, the natural resources sector can be especially affected by events relating to international political and economic developments, government regulations, energy conservation, and the success of exploration projects. Because the Fund invests primarily in the natural resources sector, it runs the risk of performing poorly during an economic downturn or a decline in demand for natural resources. Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate more than if the Fund had a broader range of investments. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the MSCI ACWI Commodity Producers Index and the MSCI ACWI. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's annual total returns from year to year for the periods indicated and by comparing the Fund's average annual total returns for different calendar periods with those of the MSCI ACWI Commodity Producers Index and the MSCI ACWI.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 12.84% (3Q2013) Lowest Quarter: – 20.51% (3Q2015) Year-to-Date (as of 3/31/16): 12.09%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Resources Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.30%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.30%
Management fee	rr_ManagementFeesOverAssets	0.50%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.22%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.87%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.10%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.77%	[2]
1 Year	rr_ExpenseExampleYear01	$ 140
3 Years	rr_ExpenseExampleYear03	331
5 Years	rr_ExpenseExampleYear05	538
10 Years	rr_ExpenseExampleYear10	1,135
1 Year	rr_ExpenseExampleNoRedemptionYear01	108
3 Years	rr_ExpenseExampleNoRedemptionYear03	297
5 Years	rr_ExpenseExampleNoRedemptionYear05	501
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,090
2012	rr_AnnualReturn2012	10.30%
2013	rr_AnnualReturn2013	3.58%
2014	rr_AnnualReturn2014	(17.34%)
2015	rr_AnnualReturn2015	(22.02%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	12.09%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2013
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	12.84%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(20.51%)
1 Year	rr_AverageAnnualReturnYear01	(22.49%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(7.18%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2011
GMO Resources Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.30%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.30%
Management fee	rr_ManagementFeesOverAssets	0.50%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.23%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.83%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.11%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.72%	[2]
1 Year	rr_ExpenseExampleYear01	$ 135
3 Years	rr_ExpenseExampleYear03	317
5 Years	rr_ExpenseExampleYear05	515
10 Years	rr_ExpenseExampleYear10	1,087
1 Year	rr_ExpenseExampleNoRedemptionYear01	103
3 Years	rr_ExpenseExampleNoRedemptionYear03	283
5 Years	rr_ExpenseExampleNoRedemptionYear05	478
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,042
1 Year	rr_AverageAnnualReturnYear01	(22.44%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(12.95%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 20, 2013
GMO Resources Fund | Class V
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.30%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.30%
Management fee	rr_ManagementFeesOverAssets	0.50%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.085%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.23%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.82%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.11%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.71%	[2]
1 Year	rr_ExpenseExampleYear01	$ 133
3 Years	rr_ExpenseExampleYear03	314
5 Years	rr_ExpenseExampleYear05	510
10 Years	rr_ExpenseExampleYear10	1,075
1 Year	rr_ExpenseExampleNoRedemptionYear01	102
3 Years	rr_ExpenseExampleNoRedemptionYear03	280
5 Years	rr_ExpenseExampleNoRedemptionYear05	473
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,030
GMO Resources Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.30%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.30%
Management fee	rr_ManagementFeesOverAssets	0.50%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.23%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.79%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.11%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.68%	[2]
1 Year	rr_ExpenseExampleYear01	$ 130
3 Years	rr_ExpenseExampleYear03	304
5 Years	rr_ExpenseExampleYear05	493
10 Years	rr_ExpenseExampleYear10	1,040
1 Year	rr_ExpenseExampleNoRedemptionYear01	99
3 Years	rr_ExpenseExampleNoRedemptionYear03	271
5 Years	rr_ExpenseExampleNoRedemptionYear05	457
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 995
GMO Resources Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(22.90%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(8.47%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2011
GMO Resources Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(12.07%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(5.08%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2011
GMO Resources Fund | MSCI ACWI Commodity Producers Index (Fund benchmark) (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(25.83%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(9.33%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2011
GMO Resources Fund | MSCI ACWI Commodity Producers Index (Fund benchmark) (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(25.83%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(13.75%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 20, 2013
GMO Resources Fund | MSCI ACWI (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.36%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	10.03%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2011
GMO Resources Fund | MSCI ACWI (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.36%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	5.97%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 20, 2013

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the portion of its "Specified Operating Expenses" (as defined below) that exceeds 0.10% of the Fund's average daily net assets. "Specified Operating Expenses" means only the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

XML

GMO International Equity Allocation Fund

GMO INTERNATIONAL EQUITY ALLOCATION FUND

Investment objective

Total return greater than that of its benchmark, the MSCI ACWI ex USA.

Fees and expenses

The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees	GMO International Equity Allocation Fund Class III
Purchase premium (as a percentage of amount invested)	0.25%
Redemption fee (as a percentage of amount redeemed)	0.25%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO International Equity Allocation Fund Class III
Management fee	none
Shareholder service fee	none
Other expenses	0.01%
Acquired fund fees and expenses (underlying fund expenses)	0.79%	[1]
Total annual fund operating expenses	0.80%
Expense reimbursement	(0.01%)	[2]
Total annual fund operating expenses	0.79%	[3]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO International Equity Allocation Fund | Class III | USD ($)	131	316	515	1,092

If you do not sell your shares

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO International Equity Allocation Fund | Class III | USD ($)	105	287	485	1,055

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 14% of the average value of its portfolio.

Principal investment strategies

The Fund is a fund of funds and invests primarily in equities traded in non-U.S. markets (including emerging markets) through shares of the Equity Funds, Alpha Only Fund and Risk Premium Fund (collectively, the "underlying GMO Funds") (see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Asset Allocation Funds"). The Fund also may invest directly in securities (including other underlying funds) and derivatives.

GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund's allocations to particular underlying GMO Funds. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund's holdings of the underlying GMO Funds in response to changes in GMO's investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund's investments. The factors GMO considers and investment methods GMO uses can change over time.

Under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities (see "Name Policies"). The term "equities" refers to direct and indirect (e.g., through the underlying GMO Funds) investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts.

The Fund may invest in securities of companies of any market capitalization.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 21.94% (2Q2009)
Lowest Quarter: – 20.16% (3Q2008)
Year-to-Date (as of 3/31/16): 1.31%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO International Equity Allocation Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(9.35%)	0.58%	2.59%	6.49%	Oct. 11, 1996
Class III | Return After Taxes on Distributions	(10.65%)	(0.32%)	1.01%	4.87%	Oct. 11, 1996
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(3.64%)	0.82%	2.50%	5.29%	Oct. 11, 1996
MSCI ACWI ex USA (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(5.66%)	1.06%	2.92%	4.64%	Oct. 11, 1996

[1] These indirect expenses include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.69% and 0.10%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO International Equity Allocation Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO INTERNATIONAL EQUITY ALLOCATION FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return greater than that of its benchmark, the MSCI ACWI ex USA.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 14% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	14.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund is a fund of funds and invests primarily in equities traded in non-U.S. markets (including emerging markets) through shares of the Equity Funds, Alpha Only Fund and Risk Premium Fund (collectively, the "underlying GMO Funds") (see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Asset Allocation Funds"). The Fund also may invest directly in securities (including other underlying funds) and derivatives. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund's allocations to particular underlying GMO Funds. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund's holdings of the underlying GMO Funds in response to changes in GMO's investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund's investments. The factors GMO considers and investment methods GMO uses can change over time. Under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities (see "Name Policies"). The term "equities" refers to direct and indirect (e.g., through the underlying GMO Funds) investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The Fund may invest in securities of companies of any market capitalization. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 21.94% (2Q2009) Lowest Quarter: – 20.16% (3Q2008) Year-to-Date (as of 3/31/16): 1.31%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO International Equity Allocation Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.25%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.25%
Management fee	rr_ManagementFeesOverAssets	none
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.01%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.79%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.80%
Expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.79%	[3]
1 Year	rr_ExpenseExampleYear01	$ 131
3 Years	rr_ExpenseExampleYear03	316
5 Years	rr_ExpenseExampleYear05	515
10 Years	rr_ExpenseExampleYear10	1,092
1 Year	rr_ExpenseExampleNoRedemptionYear01	105
3 Years	rr_ExpenseExampleNoRedemptionYear03	287
5 Years	rr_ExpenseExampleNoRedemptionYear05	485
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,055
2006	rr_AnnualReturn2006	25.92%
2007	rr_AnnualReturn2007	17.44%
2008	rr_AnnualReturn2008	(41.39%)
2009	rr_AnnualReturn2009	28.07%
2010	rr_AnnualReturn2010	13.03%
2011	rr_AnnualReturn2011	(11.25%)
2012	rr_AnnualReturn2012	17.04%
2013	rr_AnnualReturn2013	16.57%
2014	rr_AnnualReturn2014	(6.22%)
2015	rr_AnnualReturn2015	(8.89%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	1.31%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	21.94%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(20.16%)
1 Year	rr_AverageAnnualReturnYear01	(9.35%)
5 Years	rr_AverageAnnualReturnYear05	0.58%
10 Years	rr_AverageAnnualReturnYear10	2.59%
Incept.	rr_AverageAnnualReturnSinceInception	6.49%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 11, 1996
GMO International Equity Allocation Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(10.65%)
5 Years	rr_AverageAnnualReturnYear05	(0.32%)
10 Years	rr_AverageAnnualReturnYear10	1.01%
Incept.	rr_AverageAnnualReturnSinceInception	4.87%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 11, 1996
GMO International Equity Allocation Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(3.64%)
5 Years	rr_AverageAnnualReturnYear05	0.82%
10 Years	rr_AverageAnnualReturnYear10	2.50%
Incept.	rr_AverageAnnualReturnSinceInception	5.29%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 11, 1996
GMO International Equity Allocation Fund | MSCI ACWI ex USA (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(5.66%)
5 Years	rr_AverageAnnualReturnYear05	1.06%
10 Years	rr_AverageAnnualReturnYear10	2.92%
Incept.	rr_AverageAnnualReturnSinceInception	4.64%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 11, 1996

[1] These indirect expenses include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.69% and 0.10%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

XML

GMO International Developed Equity Allocation Fund

GMO INTERNATIONAL DEVELOPED EQUITY ALLOCATION FUND

Investment objective

Total return greater than that of its benchmark, the MSCI EAFE Index.

Fees and expenses

The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees	GMO International Developed Equity Allocation Fund Class III
Purchase premium (as a percentage of amount invested)	0.08%
Redemption fee (as a percentage of amount redeemed)	0.08%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO International Developed Equity Allocation Fund Class III
Management fee	none
Shareholder service fee	none
Other expenses	0.01%
Acquired fund fees and expenses (underlying fund expenses)	0.65%	[1]
Total annual fund operating expenses	0.66%
Expense reimbursement	(0.01%)	[2]
Total annual fund operating expenses	0.65%	[3]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO International Developed Equity Allocation Fund | Class III | USD ($)	83	238	407	896

If you do not sell your shares

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO International Developed Equity Allocation Fund | Class III | USD ($)	74	229	397	884

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 14% of the average value of its portfolio.

Principal investment strategies

The Fund is a fund of funds and invests primarily in equities traded in non-U.S. markets (including emerging markets) through shares of the Equity Funds, Alpha Only Fund and Risk Premium Fund (collectively, the “underlying GMO Funds”) (see “Additional Information About the Funds’ Investment Strategies, Risks, and Expenses — Asset Allocation Funds”). The Fund also may invest directly in securities (including other underlying funds) and derivatives.

GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund’s allocations to particular underlying GMO Funds. An important component of those forecasts is GMO’s expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund’s holdings of the underlying GMO Funds in response to changes in GMO’s investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund’s investments. The factors GMO considers and investment methods GMO uses can change over time.

Under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities (see “Name Policies”). In addition, under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities tied economically to developed markets (see “Name Policies”). The Fund also may invest in equities in emerging markets, but those investments typically will represent 10% or less of the Fund’s net assets measured at the time of purchase. The term “equities” refers to direct and indirect (e.g., through underlying GMO Funds) investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The term “developed markets” means those countries included in the MSCI World Index, a global developed markets equity index, and countries with similar characteristics (e.g., countries that have sustained economic development, sufficient liquidity for listed companies and accessible markets).

The Fund may invest in securities of companies of any market capitalization.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying Funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 19.55% (2Q2009)
Lowest Quarter: – 18.80% (3Q2008)
Year-to-Date (as of 3/31/16): – 1.20%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO International Developed Equity Allocation Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(6.77%)	2.97%		2.16%	Jun. 05, 2006
Class III | Return After Taxes on Distributions	(7.21%)	2.41%		1.14%	Jun. 05, 2006
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(2.94%)	2.56%		1.90%	Jun. 05, 2006
MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.81%)	3.60%		2.02%	Jun. 05, 2006

[1] These indirect expenses include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.62% and 0.03%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO International Developed Equity Allocation Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO INTERNATIONAL DEVELOPED EQUITY ALLOCATION FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return greater than that of its benchmark, the MSCI EAFE Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 14% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	14.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund is a fund of funds and invests primarily in equities traded in non-U.S. markets (including emerging markets) through shares of the Equity Funds, Alpha Only Fund and Risk Premium Fund (collectively, the “underlying GMO Funds”) (see “Additional Information About the Funds’ Investment Strategies, Risks, and Expenses — Asset Allocation Funds”). The Fund also may invest directly in securities (including other underlying funds) and derivatives. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund’s allocations to particular underlying GMO Funds. An important component of those forecasts is GMO’s expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund’s holdings of the underlying GMO Funds in response to changes in GMO’s investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund’s investments. The factors GMO considers and investment methods GMO uses can change over time. Under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities (see “Name Policies”). In addition, under normal circumstances, the Fund invests (including through investment in the underlying GMO Funds) at least 80% of its assets in equities tied economically to developed markets (see “Name Policies”). The Fund also may invest in equities in emerging markets, but those investments typically will represent 10% or less of the Fund’s net assets measured at the time of purchase. The term “equities” refers to direct and indirect (e.g., through underlying GMO Funds) investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The term “developed markets” means those countries included in the MSCI World Index, a global developed markets equity index, and countries with similar characteristics (e.g., countries that have sustained economic development, sufficient liquidity for listed companies and accessible markets). The Fund may invest in securities of companies of any market capitalization. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying Funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying Funds may affect the performance of those underlying funds more than if they were diversified investment companies.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 19.55% (2Q2009) Lowest Quarter: – 18.80% (3Q2008) Year-to-Date (as of 3/31/16): – 1.20%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO International Developed Equity Allocation Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.08%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.08%
Management fee	rr_ManagementFeesOverAssets	none
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.01%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.65%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.66%
Expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.65%	[3]
1 Year	rr_ExpenseExampleYear01	$ 83
3 Years	rr_ExpenseExampleYear03	238
5 Years	rr_ExpenseExampleYear05	407
10 Years	rr_ExpenseExampleYear10	896
1 Year	rr_ExpenseExampleNoRedemptionYear01	74
3 Years	rr_ExpenseExampleNoRedemptionYear03	229
5 Years	rr_ExpenseExampleNoRedemptionYear05	397
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 884
2007	rr_AnnualReturn2007	13.29%
2008	rr_AnnualReturn2008	(37.91%)
2009	rr_AnnualReturn2009	19.78%
2010	rr_AnnualReturn2010	10.86%
2011	rr_AnnualReturn2011	(9.43%)
2012	rr_AnnualReturn2012	17.13%
2013	rr_AnnualReturn2013	24.25%
2014	rr_AnnualReturn2014	(5.82%)
2015	rr_AnnualReturn2015	(6.62%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(1.20%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	19.55%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(18.80%)
1 Year	rr_AverageAnnualReturnYear01	(6.77%)
5 Years	rr_AverageAnnualReturnYear05	2.97%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	2.16%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 05, 2006
GMO International Developed Equity Allocation Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(7.21%)
5 Years	rr_AverageAnnualReturnYear05	2.41%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.14%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 05, 2006
GMO International Developed Equity Allocation Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.94%)
5 Years	rr_AverageAnnualReturnYear05	2.56%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.90%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 05, 2006
GMO International Developed Equity Allocation Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)
5 Years	rr_AverageAnnualReturnYear05	3.60%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	2.02%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 05, 2006

[1] These indirect expenses include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.62% and 0.03%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

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GMO Tax-Managed International Equities Fund

GMO TAX-MANAGED INTERNATIONAL EQUITIES FUND

Investment objective

High after-tax total return.

Fees and expenses

The table below describes the fees and expenses that you may bear if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Tax-Managed International Equities Fund Class III
Management fee	0.50%	[1]
Shareholder service fee	0.15%	[1]
Other expenses	0.15%
Total annual fund operating expenses	0.80%
Expense reimbursement/waiver	(0.14%)	[1]
Total annual fund operating expenses	0.66%	[2]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amount shown reflects the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Tax-Managed International Equities Fund | Class III | USD ($)	67	244	435	988

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Tax-Managed International Equities Fund | Class III | USD ($)	67	244	435	988

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 79% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 55% of the average value of its portfolio.

Principal investment strategies

GMO seeks to achieve the Fund's investment objective by investing primarily in a portfolio of equities in international equity markets. GMO selects the securities the Fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, the overall global economy, and governmental policies.

In selecting securities for the Fund, GMO uses a combination of investment methods to identify securities that GMO believes have positive return potential relative to other securities in international equity markets. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to international equity markets. GMO also uses its multi-year return forecasts for asset classes and other groups of securities in its investment process and may adjust the Fund's portfolio based on factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, region, or currency. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark.

GMO may consider the tax effects of a proposed trade in conjunction with the return forecast of the identified equities, and their potential contribution to the overall portfolio. GMO also may consider the Fund's realized and unrealized gains and losses, and current market conditions, because these factors also influence the decision to buy or sell securities.

As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, forward currency contracts, and swap contracts. In addition, the Fund may lend its portfolio securities.

The Fund typically invests directly and indirectly (e.g., through underlying funds or derivatives) in equities of companies tied economically to countries other than the United States, including both developed and emerging countries. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in equities (see "Name Policies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. There can be no assurance that the Fund’s tax management strategies will be effective, and you may incur tax liabilities that exceed your economic return. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund’s benchmark (which is computed by GMO) and a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 21.51% (2Q2009)
Lowest Quarter: – 20.34% (3Q2008)
Year-to-Date (as of 3/31/16): – 2.81%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Tax-Managed International Equities Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(5.35%)	2.94%	2.85%	5.89%	Jul. 29, 1998
Class III | Return After Taxes on Distributions	(5.87%)	2.48%	2.23%	5.31%	Jul. 29, 1998
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(2.25%)	2.59%	2.69%	5.12%	Jul. 29, 1998
MSCI EAFE Index (after tax) (Fund benchmark) (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(2.19%)	2.32%	1.93%	2.84%	Jul. 29, 1998
MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.81%)	3.60%	3.03%	3.71%	Jul. 29, 1998

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund’s management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund’s direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[2] after expense reimbursement/waiver

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Tax-Managed International Equities Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO TAX-MANAGED INTERNATIONAL EQUITIES FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	High after-tax total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 79% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 55% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	79.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amount shown reflects the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO seeks to achieve the Fund's investment objective by investing primarily in a portfolio of equities in international equity markets. GMO selects the securities the Fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, the overall global economy, and governmental policies. In selecting securities for the Fund, GMO uses a combination of investment methods to identify securities that GMO believes have positive return potential relative to other securities in international equity markets. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to international equity markets. GMO also uses its multi-year return forecasts for asset classes and other groups of securities in its investment process and may adjust the Fund's portfolio based on factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, region, or currency. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. GMO may consider the tax effects of a proposed trade in conjunction with the return forecast of the identified equities, and their potential contribution to the overall portfolio. GMO also may consider the Fund's realized and unrealized gains and losses, and current market conditions, because these factors also influence the decision to buy or sell securities. As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, forward currency contracts, and swap contracts. In addition, the Fund may lend its portfolio securities. The Fund typically invests directly and indirectly (e.g., through underlying funds or derivatives) in equities of companies tied economically to countries other than the United States, including both developed and emerging countries. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in equities (see "Name Policies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. There can be no assurance that the Fund’s tax management strategies will be effective, and you may incur tax liabilities that exceed your economic return. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund’s benchmark (which is computed by GMO) and a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund’s benchmark (which is computed by GMO) and a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 21.51% (2Q2009) Lowest Quarter: – 20.34% (3Q2008) Year-to-Date (as of 3/31/16): – 2.81%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Tax-Managed International Equities Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.50%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.15%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.80%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.14%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.66%	[2]
1 Year	rr_ExpenseExampleYear01	$ 67
3 Years	rr_ExpenseExampleYear03	244
5 Years	rr_ExpenseExampleYear05	435
10 Years	rr_ExpenseExampleYear10	988
1 Year	rr_ExpenseExampleNoRedemptionYear01	67
3 Years	rr_ExpenseExampleNoRedemptionYear03	244
5 Years	rr_ExpenseExampleNoRedemptionYear05	435
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 988
2006	rr_AnnualReturn2006	25.42%
2007	rr_AnnualReturn2007	13.42%
2008	rr_AnnualReturn2008	(39.20%)
2009	rr_AnnualReturn2009	20.98%
2010	rr_AnnualReturn2010	9.49%
2011	rr_AnnualReturn2011	(8.33%)
2012	rr_AnnualReturn2012	14.68%
2013	rr_AnnualReturn2013	25.62%
2014	rr_AnnualReturn2014	(7.54%)
2015	rr_AnnualReturn2015	(5.35%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(2.81%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	21.51%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(20.34%)
1 Year	rr_AverageAnnualReturnYear01	(5.35%)
5 Years	rr_AverageAnnualReturnYear05	2.94%
10 Years	rr_AverageAnnualReturnYear10	2.85%
Incept.	rr_AverageAnnualReturnSinceInception	5.89%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 1998
GMO Tax-Managed International Equities Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(5.87%)
5 Years	rr_AverageAnnualReturnYear05	2.48%
10 Years	rr_AverageAnnualReturnYear10	2.23%
Incept.	rr_AverageAnnualReturnSinceInception	5.31%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 1998
GMO Tax-Managed International Equities Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.25%)
5 Years	rr_AverageAnnualReturnYear05	2.59%
10 Years	rr_AverageAnnualReturnYear10	2.69%
Incept.	rr_AverageAnnualReturnSinceInception	5.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 1998
GMO Tax-Managed International Equities Fund | MSCI EAFE Index (after tax) (Fund benchmark) (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.19%)
5 Years	rr_AverageAnnualReturnYear05	2.32%
10 Years	rr_AverageAnnualReturnYear10	1.93%
Incept.	rr_AverageAnnualReturnSinceInception	2.84%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 1998
GMO Tax-Managed International Equities Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)
5 Years	rr_AverageAnnualReturnYear05	3.60%
10 Years	rr_AverageAnnualReturnYear10	3.03%
Incept.	rr_AverageAnnualReturnSinceInception	3.71%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 1998

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund’s management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund’s direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[2] after expense reimbursement/waiver

XML

GMO International Equity Fund

GMO INTERNATIONAL EQUITY FUND

Investment objective

High total return.

Fees and expenses

The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO International Equity Fund		Class II	Class III	Class IV
Management fee	[1]	0.50%	0.50%	0.50%
Shareholder service fee	[1]	0.22%	0.15%	0.09%
Other expenses		0.04%	0.04%	0.04%
Total annual fund operating expenses		0.76%	0.69%	0.63%
Expense reimbursement/waiver	[1]	(0.04%)	(0.04%)	(0.04%)
Total annual fund operating expenses	[2]	0.72%	0.65%	0.59%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - GMO International Equity Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class II	74	239	418	939
Class III	66	217	380	855
Class IV	60	198	347	783

Expense Example, No Redemption - GMO International Equity Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class II	74	239	418	939
Class III	66	217	380	855
Class IV	60	198	347	783

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 75% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 59% of the average value of its portfolio.

Principal investment strategies

GMO seeks to achieve the Fund's investment objective by investing primarily in a portfolio of non-U.S. developed market equities. GMO selects the securities the Fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, the overall global economy, and governmental policies.

In selecting securities for the Fund, GMO uses a combination of investment methods to identify securities that GMO believes have positive return potential relative to other securities in international equity markets. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to international equity markets. GMO also uses its multi-year return forecasts for asset classes and other groups of securities in its investment process and may adjust the Fund's portfolio based on factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, region, or currency. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark.

As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, forward currency contracts, and swap contracts. In addition, the Fund may lend its portfolio securities.

Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in equities (see "Name Policies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 22.40% (2Q2009)
Lowest Quarter: – 19.13% (3Q2011)
Year-to-Date (as of 3/31/16): – 2.34%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO International Equity Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class II	(5.65%)	2.38%	1.89%	5.77%	Sep. 26, 1996
Class II | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.81%)	3.60%	3.03%	4.39%	Sep. 26, 1996
Class III	(5.61%)	2.45%	1.96%	7.38%	Mar. 31, 1987
Class III | Return After Taxes on Distributions	(6.04%)	1.79%	1.01%	5.90%	Mar. 31, 1987
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(2.31%)	2.20%	2.01%	5.97%	Mar. 31, 1987
Class III | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.81%)	3.60%	3.03%	5.01%	Mar. 31, 1987
Class IV	(5.56%)	2.52%	2.03%	6.12%	Jan. 09, 1998
Class IV | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.81%)	3.60%	3.03%	4.65%	Jan. 09, 1998

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO International Equity Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO INTERNATIONAL EQUITY FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	High total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 75% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 59% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	75.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO seeks to achieve the Fund's investment objective by investing primarily in a portfolio of non-U.S. developed market equities. GMO selects the securities the Fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, the overall global economy, and governmental policies. In selecting securities for the Fund, GMO uses a combination of investment methods to identify securities that GMO believes have positive return potential relative to other securities in international equity markets. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to international equity markets. GMO also uses its multi-year return forecasts for asset classes and other groups of securities in its investment process and may adjust the Fund's portfolio based on factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, region, or currency. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, forward currency contracts, and swap contracts. In addition, the Fund may lend its portfolio securities. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in equities (see "Name Policies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 22.40% (2Q2009) Lowest Quarter: – 19.13% (3Q2011) Year-to-Date (as of 3/31/16): – 2.34%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO International Equity Fund | Class II
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.50%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.22%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.04%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.76%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.72%	[2]
1 Year	rr_ExpenseExampleYear01	$ 74
3 Years	rr_ExpenseExampleYear03	239
5 Years	rr_ExpenseExampleYear05	418
10 Years	rr_ExpenseExampleYear10	939
1 Year	rr_ExpenseExampleNoRedemptionYear01	74
3 Years	rr_ExpenseExampleNoRedemptionYear03	239
5 Years	rr_ExpenseExampleNoRedemptionYear05	418
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 939
1 Year	rr_AverageAnnualReturnYear01	(5.65%)
5 Years	rr_AverageAnnualReturnYear05	2.38%
10 Years	rr_AverageAnnualReturnYear10	1.89%
Incept.	rr_AverageAnnualReturnSinceInception	5.77%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 26, 1996
GMO International Equity Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.50%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.04%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.69%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.65%	[2]
1 Year	rr_ExpenseExampleYear01	$ 66
3 Years	rr_ExpenseExampleYear03	217
5 Years	rr_ExpenseExampleYear05	380
10 Years	rr_ExpenseExampleYear10	855
1 Year	rr_ExpenseExampleNoRedemptionYear01	66
3 Years	rr_ExpenseExampleNoRedemptionYear03	217
5 Years	rr_ExpenseExampleNoRedemptionYear05	380
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 855
2006	rr_AnnualReturn2006	25.33%
2007	rr_AnnualReturn2007	9.89%
2008	rr_AnnualReturn2008	(38.78%)
2009	rr_AnnualReturn2009	18.65%
2010	rr_AnnualReturn2010	7.59%
2011	rr_AnnualReturn2011	(10.33%)
2012	rr_AnnualReturn2012	14.43%
2013	rr_AnnualReturn2013	24.62%
2014	rr_AnnualReturn2014	(6.49%)
2015	rr_AnnualReturn2015	(5.61%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(2.34%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	22.40%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(19.13%)
1 Year	rr_AverageAnnualReturnYear01	(5.61%)
5 Years	rr_AverageAnnualReturnYear05	2.45%
10 Years	rr_AverageAnnualReturnYear10	1.96%
Incept.	rr_AverageAnnualReturnSinceInception	7.38%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 31, 1987
GMO International Equity Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.50%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.09%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.04%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.63%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.59%	[2]
1 Year	rr_ExpenseExampleYear01	$ 60
3 Years	rr_ExpenseExampleYear03	198
5 Years	rr_ExpenseExampleYear05	347
10 Years	rr_ExpenseExampleYear10	783
1 Year	rr_ExpenseExampleNoRedemptionYear01	60
3 Years	rr_ExpenseExampleNoRedemptionYear03	198
5 Years	rr_ExpenseExampleNoRedemptionYear05	347
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 783
1 Year	rr_AverageAnnualReturnYear01	(5.56%)
5 Years	rr_AverageAnnualReturnYear05	2.52%
10 Years	rr_AverageAnnualReturnYear10	2.03%
Incept.	rr_AverageAnnualReturnSinceInception	6.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998
GMO International Equity Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(6.04%)
5 Years	rr_AverageAnnualReturnYear05	1.79%
10 Years	rr_AverageAnnualReturnYear10	1.01%
Incept.	rr_AverageAnnualReturnSinceInception	5.90%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 31, 1987
GMO International Equity Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.31%)
5 Years	rr_AverageAnnualReturnYear05	2.20%
10 Years	rr_AverageAnnualReturnYear10	2.01%
Incept.	rr_AverageAnnualReturnSinceInception	5.97%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 31, 1987
GMO International Equity Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class II
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)
5 Years	rr_AverageAnnualReturnYear05	3.60%
10 Years	rr_AverageAnnualReturnYear10	3.03%
Incept.	rr_AverageAnnualReturnSinceInception	4.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 26, 1996
GMO International Equity Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)
5 Years	rr_AverageAnnualReturnYear05	3.60%
10 Years	rr_AverageAnnualReturnYear10	3.03%
Incept.	rr_AverageAnnualReturnSinceInception	5.01%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 31, 1987
GMO International Equity Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)
5 Years	rr_AverageAnnualReturnYear05	3.60%
10 Years	rr_AverageAnnualReturnYear10	3.03%
Incept.	rr_AverageAnnualReturnSinceInception	4.65%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

XML

GMO International Large/Mid Cap Equity Fund

GMO INTERNATIONAL LARGE/MID CAP EQUITY FUND

Investment objective

High total return.

Fees and expenses

The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO International Large/Mid Cap Equity Fund		Class III	Class IV	Class VI
Management fee	[1]	0.38%	0.38%	0.38%
Shareholder service fee	[1]	0.15%	0.09%	0.055%
Other expenses		0.07%	0.07%	0.07%
Total annual fund operating expenses		0.60%	0.54%	0.51%
Expense reimbursement/waiver	[1]	(0.07%)	(0.07%)	(0.07%)
Total annual fund operating expenses	[2]	0.53%	0.47%	0.44%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - GMO International Large/Mid Cap Equity Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	54	185	328	743
Class IV	48	166	295	670
Class VI	45	156	278	634

Expense Example, No Redemption - GMO International Large/Mid Cap Equity Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	54	185	328	743
Class IV	48	166	295	670
Class VI	45	156	278	634

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 88% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 70% of the average value of its portfolio.

Principal investment strategies

GMO seeks to achieve the Fund's investment objective by investing primarily in a portfolio of non-U.S. developed market equities. GMO selects the securities the Fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, the overall global economy, and governmental policies.

In selecting securities for the Fund, GMO uses a combination of investment methods to identify securities that GMO believes have positive return potential relative to other securities in international equity markets. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to international equity markets. GMO also uses its multi-year return forecasts for asset classes and other groups of securities in its investment process and may adjust the Fund's portfolio based on factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, region, or currency. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark.

As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, forward currency contracts, and swap contracts. In addition, the Fund may lend its portfolio securities.

Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in equities (see "Name Policies"). In addition, under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in equities of large- and mid-cap companies (see "Name Policies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The term "large- and mid-cap companies" means non-U.S. companies that issue stocks included in the MSCI Standard Indices and international stock indices that target approximately 85% of each market's free-float adjusted market capitalization, and companies with similar market capitalizations.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 22.30% (2Q2009)
Lowest Quarter: – 19.92% (3Q2008)
Year-to-Date (as of 3/31/16): – 2.15%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO International Large/Mid Cap Equity Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	[1]	(5.82%)	2.88%	2.48%	6.54%	Jan. 29, 2002
Class III | Return After Taxes on Distributions	[1]	(6.31%)	1.91%	1.59%	5.70%	Jan. 29, 2002
Class III | Return After Taxes on Distributions and Sale of Fund Shares	[1]	(2.54%)	2.56%	2.23%	5.60%	Jan. 29, 2002
Class III | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	[1]	(0.81%)	3.60%	3.03%	6.03%	Jan. 29, 2002
Class IV	[1]	(5.77%)	2.94%	2.55%	6.61%	Jun. 30, 2003
Class IV | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	[1]	(0.81%)	3.60%	3.03%	7.00%	Jun. 30, 2003
Class VI	[1]	(5.74%)	2.97%		1.80%	Mar. 28, 2006
Class VI | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	[1]	(0.81%)	3.60%		2.24%	Mar. 28, 2006

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

[1] The Fund is the successor to GMO International Disciplined Equity Fund, a former series of GMO Trust that had an investment objective and investment policies and restrictions substantially identical to those of the Fund. Performance of the Fund through September 16, 2005 is that of GMO International Disciplined Equity Fund and reflects GMO International Disciplined Equity Fund's annual operating expenses (0.02% higher than those of the Fund).

[1] The Fund is the successor to GMO International Disciplined Equity Fund, a former series of GMO Trust that had an investment objective and investment policies and restrictions substantially identical to those of the Fund. Performance of the Fund through September 16, 2005 is that of GMO International Disciplined Equity Fund and reflects GMO International Disciplined Equity Fund's annual operating expenses (0.02% higher than those of the Fund).

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO International Large/Mid Cap Equity Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO INTERNATIONAL LARGE/MID CAP EQUITY FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	High total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 88% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 70% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	88.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO seeks to achieve the Fund's investment objective by investing primarily in a portfolio of non-U.S. developed market equities. GMO selects the securities the Fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, the overall global economy, and governmental policies. In selecting securities for the Fund, GMO uses a combination of investment methods to identify securities that GMO believes have positive return potential relative to other securities in international equity markets. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to international equity markets. GMO also uses its multi-year return forecasts for asset classes and other groups of securities in its investment process and may adjust the Fund's portfolio based on factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, region, or currency. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, forward currency contracts, and swap contracts. In addition, the Fund may lend its portfolio securities. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in equities (see "Name Policies"). In addition, under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in equities of large- and mid-cap companies (see "Name Policies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The term "large- and mid-cap companies" means non-U.S. companies that issue stocks included in the MSCI Standard Indices and international stock indices that target approximately 85% of each market's free-float adjusted market capitalization, and companies with similar market capitalizations. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 22.30% (2Q2009) Lowest Quarter: – 19.92% (3Q2008) Year-to-Date (as of 3/31/16): – 2.15%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO International Large/Mid Cap Equity Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.38%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.07%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.60%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.07%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.53%	[2]
1 Year	rr_ExpenseExampleYear01	$ 54
3 Years	rr_ExpenseExampleYear03	185
5 Years	rr_ExpenseExampleYear05	328
10 Years	rr_ExpenseExampleYear10	743
1 Year	rr_ExpenseExampleNoRedemptionYear01	54
3 Years	rr_ExpenseExampleNoRedemptionYear03	185
5 Years	rr_ExpenseExampleNoRedemptionYear05	328
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 743
2006	rr_AnnualReturn2006	24.78%	[3]
2007	rr_AnnualReturn2007	11.01%	[3]
2008	rr_AnnualReturn2008	(40.05%)	[3]
2009	rr_AnnualReturn2009	21.06%	[3]
2010	rr_AnnualReturn2010	10.29%	[3]
2011	rr_AnnualReturn2011	(9.08%)	[3]
2012	rr_AnnualReturn2012	15.84%	[3]
2013	rr_AnnualReturn2013	25.06%	[3]
2014	rr_AnnualReturn2014	(7.11%)	[3]
2015	rr_AnnualReturn2015	(5.82%)	[3]
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(2.15%)	[3]
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	22.30%	[3]
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(19.92%)	[3]
1 Year	rr_AverageAnnualReturnYear01	(5.82%)	[3]
5 Years	rr_AverageAnnualReturnYear05	2.88%	[3]
10 Years	rr_AverageAnnualReturnYear10	2.48%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	6.54%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 29, 2002	[3]
GMO International Large/Mid Cap Equity Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.38%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.09%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.07%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.54%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.07%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.47%	[2]
1 Year	rr_ExpenseExampleYear01	$ 48
3 Years	rr_ExpenseExampleYear03	166
5 Years	rr_ExpenseExampleYear05	295
10 Years	rr_ExpenseExampleYear10	670
1 Year	rr_ExpenseExampleNoRedemptionYear01	48
3 Years	rr_ExpenseExampleNoRedemptionYear03	166
5 Years	rr_ExpenseExampleNoRedemptionYear05	295
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 670
1 Year	rr_AverageAnnualReturnYear01	(5.77%)	[3]
5 Years	rr_AverageAnnualReturnYear05	2.94%	[3]
10 Years	rr_AverageAnnualReturnYear10	2.55%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	6.61%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 30, 2003	[3]
GMO International Large/Mid Cap Equity Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.38%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.07%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.51%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.07%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.44%	[2]
1 Year	rr_ExpenseExampleYear01	$ 45
3 Years	rr_ExpenseExampleYear03	156
5 Years	rr_ExpenseExampleYear05	278
10 Years	rr_ExpenseExampleYear10	634
1 Year	rr_ExpenseExampleNoRedemptionYear01	45
3 Years	rr_ExpenseExampleNoRedemptionYear03	156
5 Years	rr_ExpenseExampleNoRedemptionYear05	278
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 634
1 Year	rr_AverageAnnualReturnYear01	(5.74%)	[3]
5 Years	rr_AverageAnnualReturnYear05	2.97%	[3]
10 Years	rr_AverageAnnualReturnYear10		[3]
Incept.	rr_AverageAnnualReturnSinceInception	1.80%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 28, 2006	[3]
GMO International Large/Mid Cap Equity Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(6.31%)	[3]
5 Years	rr_AverageAnnualReturnYear05	1.91%	[3]
10 Years	rr_AverageAnnualReturnYear10	1.59%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	5.70%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 29, 2002	[3]
GMO International Large/Mid Cap Equity Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.54%)	[3]
5 Years	rr_AverageAnnualReturnYear05	2.56%	[3]
10 Years	rr_AverageAnnualReturnYear10	2.23%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	5.60%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 29, 2002	[3]
GMO International Large/Mid Cap Equity Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)	[3]
5 Years	rr_AverageAnnualReturnYear05	3.60%	[3]
10 Years	rr_AverageAnnualReturnYear10	3.03%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	6.03%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 29, 2002	[3]
GMO International Large/Mid Cap Equity Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)	[3]
5 Years	rr_AverageAnnualReturnYear05	3.60%	[3]
10 Years	rr_AverageAnnualReturnYear10	3.03%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	7.00%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 30, 2003	[3]
GMO International Large/Mid Cap Equity Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)	[3]
5 Years	rr_AverageAnnualReturnYear05	3.60%	[3]
10 Years	rr_AverageAnnualReturnYear10		[3]
Incept.	rr_AverageAnnualReturnSinceInception	2.24%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 28, 2006	[3]

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

[3] The Fund is the successor to GMO International Disciplined Equity Fund, a former series of GMO Trust that had an investment objective and investment policies and restrictions substantially identical to those of the Fund. Performance of the Fund through September 16, 2005 is that of GMO International Disciplined Equity Fund and reflects GMO International Disciplined Equity Fund's annual operating expenses (0.02% higher than those of the Fund).

XML

GMO Foreign Fund

GMO FOREIGN FUND

Investment objective

Total return in excess of that of its benchmark, the MSCI EAFE Index.

Fees and expenses

The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Foreign Fund		Class II	Class III	Class IV
Management fee	[1]	0.60%	0.60%	0.60%
Shareholder service fee	[1]	0.22%	0.15%	0.09%
Other expenses		0.19%	0.18%	0.19%
Total annual fund operating expenses		1.01%	0.93%	0.88%
Expense reimbursement/waiver	[1]	(0.18%)	(0.17%)	(0.18%)
Total annual fund operating expenses	[2]	0.83%	0.76%	0.70%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - GMO Foreign Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class II	85	304	540	1,220
Class III	78	282	503	1,138
Class IV	72	263	470	1,068

Expense Example, No Redemption - GMO Foreign Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class II	85	304	540	1,220
Class III	78	282	503	1,138
Class IV	72	263	470	1,068

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate was 65% of the average value of its portfolio. That portfolio turnover rate excludes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management, and other short-term investments. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, including transactions in U.S. Treasury Fund, was 113% of the average value of its portfolio.

Principal investment strategies

The Fund typically invests directly and indirectly in equities of companies tied economically to countries other than the United States. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. Under normal circumstances, the Fund invests directly and indirectly (e.g., through underlying funds or derivatives) at least 80% of its assets in investments tied economically to countries other than the United States, including both developed and emerging countries (see "Name Policies").

GMO selects investments using value-based fundamental analysis that is informed by a disciplined quantitative screening process. GMO analyzes companies for financial, operational, and managerial strength and compares them to their global, regional, and industry peers. GMO also considers a company's accounting and governance practices. As part of the investment process, GMO frequently meets with management and visits companies.

The factors GMO considers and investment methods GMO uses can change over time.

In pursuing its investment objective, the Fund may (but is not obligated to) invest in a wide variety of exchange-traded and over-the-counter (OTC) derivatives, including, without limitation, forward currency contracts, futures and options, as well as exchange-traded funds (ETFs). The Fund's foreign currency exposure may differ from the currency exposure of its equity investments. The Fund may invest in securities of companies of any market capitalization and may have significant exposure to securities of issuers with smaller market capitalizations. In addition, the Fund may lend its portfolio securities.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Information on the Fund’s return after taxes is unavailable prior to June 28, 1996, the date the Fund commenced operations as a registered investment company. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 21.67% (2Q2009)
Lowest Quarter: – 19.80% (3Q2011)
Year-to-Date (as of 3/31/16): – 3.53%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Foreign Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class II	[1]	6.73%	3.36%	2.43%	6.37%	Sep. 30, 1996
Class II | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	[1]	(0.81%)	3.60%	3.03%	4.37%	Sep. 30, 1996
Class III	[1],[2]	6.80%	3.43%	2.51%	11.15%	Aug. 31, 1984
Class III | Return After Taxes on Distributions	[1],[2]	5.78%	2.63%	1.62%		Aug. 31, 1984
Class III | Return After Taxes on Distributions and Sale of Fund Shares	[1],[2]	4.62%	2.82%	2.30%		Aug. 31, 1984
Class III | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	[1],[2]	(0.81%)	3.60%	3.03%	8.75%	Aug. 31, 1984
Class IV	[1]	6.91%	3.48%	2.55%	6.31%	Jan. 09, 1998
Class IV | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	[1]	(0.81%)	3.60%	3.03%	4.65%	Jan. 09, 1998

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

[1] Information on the Fund's return after taxes is unavailable prior to June 28, 1996, the date the Fund commenced operations as a registered investment company. Prior to that date, the Fund operated as a private investment pool with investment objectives, policies, and guidelines that were substantially the same as those of the Fund.

[2] Performance of Class III shares prior to June 28, 1996 is that of the private investment pool and reflects the pool's higher annual operating expenses. The pool was not registered as an investment company and therefore was not subject to restrictions imposed on the Fund by the Investment Company Act of 1940, as amended, and the Internal Revenue Code of 1986, as amended. Had the pool been subject to these restrictions, its performance may have been adversely affected.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Foreign Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO FOREIGN FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the MSCI EAFE Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate was 65% of the average value of its portfolio. That portfolio turnover rate excludes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management, and other short-term investments. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, including transactions in U.S. Treasury Fund, was 113% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	65.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund typically invests directly and indirectly in equities of companies tied economically to countries other than the United States. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. Under normal circumstances, the Fund invests directly and indirectly (e.g., through underlying funds or derivatives) at least 80% of its assets in investments tied economically to countries other than the United States, including both developed and emerging countries (see "Name Policies"). GMO selects investments using value-based fundamental analysis that is informed by a disciplined quantitative screening process. GMO analyzes companies for financial, operational, and managerial strength and compares them to their global, regional, and industry peers. GMO also considers a company's accounting and governance practices. As part of the investment process, GMO frequently meets with management and visits companies. The factors GMO considers and investment methods GMO uses can change over time. In pursuing its investment objective, the Fund may (but is not obligated to) invest in a wide variety of exchange-traded and over-the-counter (OTC) derivatives, including, without limitation, forward currency contracts, futures and options, as well as exchange-traded funds (ETFs). The Fund's foreign currency exposure may differ from the currency exposure of its equity investments. The Fund may invest in securities of companies of any market capitalization and may have significant exposure to securities of issuers with smaller market capitalizations. In addition, the Fund may lend its portfolio securities. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Information on the Fund’s return after taxes is unavailable prior to June 28, 1996, the date the Fund commenced operations as a registered investment company. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 21.67% (2Q2009) Lowest Quarter: – 19.80% (3Q2011) Year-to-Date (as of 3/31/16): – 3.53%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Foreign Fund | Class II
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.60%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.22%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.19%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.01%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.18%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.83%	[2]
1 Year	rr_ExpenseExampleYear01	$ 85
3 Years	rr_ExpenseExampleYear03	304
5 Years	rr_ExpenseExampleYear05	540
10 Years	rr_ExpenseExampleYear10	1,220
1 Year	rr_ExpenseExampleNoRedemptionYear01	85
3 Years	rr_ExpenseExampleNoRedemptionYear03	304
5 Years	rr_ExpenseExampleNoRedemptionYear05	540
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,220
1 Year	rr_AverageAnnualReturnYear01	6.73%	[3]
5 Years	rr_AverageAnnualReturnYear05	3.36%	[3]
10 Years	rr_AverageAnnualReturnYear10	2.43%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	6.37%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 30, 1996	[3]
GMO Foreign Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.60%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.18%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.93%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.17%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.76%	[2]
1 Year	rr_ExpenseExampleYear01	$ 78
3 Years	rr_ExpenseExampleYear03	282
5 Years	rr_ExpenseExampleYear05	503
10 Years	rr_ExpenseExampleYear10	1,138
1 Year	rr_ExpenseExampleNoRedemptionYear01	78
3 Years	rr_ExpenseExampleNoRedemptionYear03	282
5 Years	rr_ExpenseExampleNoRedemptionYear05	503
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,138
2006	rr_AnnualReturn2006	27.12%
2007	rr_AnnualReturn2007	10.23%
2008	rr_AnnualReturn2008	(39.79%)
2009	rr_AnnualReturn2009	22.46%
2010	rr_AnnualReturn2010	4.77%
2011	rr_AnnualReturn2011	(11.93%)
2012	rr_AnnualReturn2012	16.17%
2013	rr_AnnualReturn2013	22.90%
2014	rr_AnnualReturn2014	(11.87%)
2015	rr_AnnualReturn2015	6.80%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(3.53%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	21.67%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(19.80%)
1 Year	rr_AverageAnnualReturnYear01	6.80%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05	3.43%	[3],[4]
10 Years	rr_AverageAnnualReturnYear10	2.51%	[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception	11.15%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 31, 1984	[3],[4]
GMO Foreign Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.60%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.09%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.19%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.88%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.18%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.70%	[2]
1 Year	rr_ExpenseExampleYear01	$ 72
3 Years	rr_ExpenseExampleYear03	263
5 Years	rr_ExpenseExampleYear05	470
10 Years	rr_ExpenseExampleYear10	1,068
1 Year	rr_ExpenseExampleNoRedemptionYear01	72
3 Years	rr_ExpenseExampleNoRedemptionYear03	263
5 Years	rr_ExpenseExampleNoRedemptionYear05	470
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,068
1 Year	rr_AverageAnnualReturnYear01	6.91%	[3]
5 Years	rr_AverageAnnualReturnYear05	3.48%	[3]
10 Years	rr_AverageAnnualReturnYear10	2.55%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	6.31%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998	[3]
GMO Foreign Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.78%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05	2.63%	[3],[4]
10 Years	rr_AverageAnnualReturnYear10	1.62%	[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception		[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 31, 1984	[3],[4]
GMO Foreign Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.62%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05	2.82%	[3],[4]
10 Years	rr_AverageAnnualReturnYear10	2.30%	[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception		[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 31, 1984	[3],[4]
GMO Foreign Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class II
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)	[3]
5 Years	rr_AverageAnnualReturnYear05	3.60%	[3]
10 Years	rr_AverageAnnualReturnYear10	3.03%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	4.37%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 30, 1996	[3]
GMO Foreign Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)	[3],[4]
5 Years	rr_AverageAnnualReturnYear05	3.60%	[3],[4]
10 Years	rr_AverageAnnualReturnYear10	3.03%	[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception	8.75%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 31, 1984	[3],[4]
GMO Foreign Fund | MSCI EAFE Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.81%)	[3]
5 Years	rr_AverageAnnualReturnYear05	3.60%	[3]
10 Years	rr_AverageAnnualReturnYear10	3.03%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	4.65%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998	[3]

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

[3] Information on the Fund's return after taxes is unavailable prior to June 28, 1996, the date the Fund commenced operations as a registered investment company. Prior to that date, the Fund operated as a private investment pool with investment objectives, policies, and guidelines that were substantially the same as those of the Fund.

[4] Performance of Class III shares prior to June 28, 1996 is that of the private investment pool and reflects the pool's higher annual operating expenses. The pool was not registered as an investment company and therefore was not subject to restrictions imposed on the Fund by the Investment Company Act of 1940, as amended, and the Internal Revenue Code of 1986, as amended. Had the pool been subject to these restrictions, its performance may have been adversely affected.

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GMO Foreign Small Companies Fund

GMO FOREIGN SMALL COMPANIES FUND

Investment objective

Total return in excess of that of its benchmark, the S&P Developed ex-U.S. Small Cap Index.

Fees and expenses

The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees - GMO Foreign Small Companies Fund	Class III	Class IV
Purchase premium (as a percentage of amount invested)	0.50%	0.50%
Redemption fee (as a percentage of amount redeemed)	0.50%	0.50%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Foreign Small Companies Fund		Class III	Class IV
Management fee	[1]	0.70%	0.70%
Shareholder service fee	[1]	0.15%	0.10%
Other expenses		0.07%	0.07%
Total annual fund operating expenses		0.92%	0.87%
Expense reimbursement/waiver	[1]	(0.06%)	(0.06%)
Total annual fund operating expenses	[2]	0.86%	0.81%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example - GMO Foreign Small Companies Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	189	392	612	1,244
Class IV	184	376	585	1,186

If you do not sell your shares

Expense Example, No Redemption - GMO Foreign Small Companies Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	137	336	551	1,170
Class IV	132	320	524	1,112

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate was 44% of the average value of its portfolio. That portfolio turnover rate excludes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management, and other short-term investments. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, including transactions in U.S. Treasury Fund, was 60% of the average value of its portfolio.

Principal investment strategies

The Fund typically invests directly and indirectly in equities of companies tied economically to countries other than the United States whose outstanding publicly traded equities are in the lowest 25% of publicly traded market capitalization (float) in a particular country at the time of investment ("small companies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The market capitalization range of companies whose equities are held by the Fund is generally within the market capitalization range of companies in the Fund's benchmark, which represents the lowest 15% of publicly traded market capitalization (float) of the S&P Broad Market Index in each country. Depending on the country, as of May 31, 2016, the market capitalization of the outstanding common stock and other stock-related securities of the largest company in a particular country included in the S&P Developed ex-U.S. Small Cap Index ranged from approximately $410 million (Argentina) to $14.4 billion (Switzerland) (based on exchange rates as of May 31, 2016). As of May 31, 2016, the publicly traded market capitalization of the largest small company (as defined by the Fund) ranged from approximately $519 million (Egypt) to $17.6 billion (Switzerland) (based on exchange rates as of May 31, 2016). Under normal circumstances, the Fund invests directly and indirectly (e.g., through underlying funds or derivatives) at least 80% of its assets in securities of small companies that are tied economically to countries other than the United States, including both developed and emerging countries (see "Name Policies").

GMO selects investments using value-based fundamental analysis that is informed by a disciplined quantitative screening process. GMO analyzes companies for financial, operational, and managerial strength and compares them to their global, regional, and industry peers. GMO also considers a company's accounting and governance practices. As part of the investment process, GMO frequently meets with management and visits companies.

The factors GMO considers and investment methods GMO uses can change over time.

In pursuing its investment objective, the Fund may (but is not obligated to) invest in a wide variety of exchange-traded and over-the-counter (OTC) derivatives, including, without limitation, forward currency contracts, futures and options, as well as exchange-traded funds (ETFs). The Fund's foreign currency exposure may differ from the currency exposure of its equity investments. In addition, the Fund may lend its portfolio securities.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 31.25% (2Q2009)
Lowest Quarter: – 24.05% (3Q2008)
Year-to-Date (as of 3/31/16): – 1.83%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Foreign Small Companies Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	[1],[2]	5.12%	4.70%	6.29%	10.34%	Jan. 04, 1995
Class III | Return After Taxes on Distributions	[1],[2]	3.97%	3.84%	4.85%		Jan. 04, 1995
Class III | Return After Taxes on Distributions and Sale of Fund Shares	[1],[2]	4.11%	3.74%	5.15%		Jan. 04, 1995
Class III | S&P Developed ex-U.S. Small Cap Index (reflects no deduction for fees, expenses, or taxes)	[1],[2]	5.92%	5.51%	5.33%	6.94%	Jan. 04, 1995
Class IV	[1],[3]	5.11%	4.75%	6.32%	10.54%	Jun. 14, 2002
Class IV | S&P Developed ex-U.S. Small Cap Index (reflects no deduction for fees, expenses, or taxes)	[1],[3]	5.92%	5.51%	5.33%	9.73%	Jun. 14, 2002

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

[1] Information on the Fund's return after taxes is unavailable prior to June 30, 2000, the date the Fund commenced operations as a registered investment company. Prior to that date, the Fund operated as a private investment pool with investment objectives, policies, and guidelines that were substantially the same as those of the Fund.

[2] Performance of Class III shares prior to June 30, 2000 is that of the private investment pool, restated to reflect the Fund's higher annual operating expenses. The pool was not registered as an investment company and therefore was not subject to certain restrictions imposed on the Fund by the Investment Company Act of 1940, as amended, and the Internal Revenue Code of 1986, as amended. Had the pool been subject to these restrictions, its performance may have been adversely affected.

[3] For the period from March 16, 2009 to August 12, 2009, no Class IV shares were outstanding. The returns shown in the table for that period are those of Class III shares, which have higher expenses.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Foreign Small Companies Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO FOREIGN SMALL COMPANIES FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the S&P Developed ex-U.S. Small Cap Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate was 44% of the average value of its portfolio. That portfolio turnover rate excludes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management, and other short-term investments. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, including transactions in U.S. Treasury Fund, was 60% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	44.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund typically invests directly and indirectly in equities of companies tied economically to countries other than the United States whose outstanding publicly traded equities are in the lowest 25% of publicly traded market capitalization (float) in a particular country at the time of investment ("small companies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The market capitalization range of companies whose equities are held by the Fund is generally within the market capitalization range of companies in the Fund's benchmark, which represents the lowest 15% of publicly traded market capitalization (float) of the S&P Broad Market Index in each country. Depending on the country, as of May 31, 2016, the market capitalization of the outstanding common stock and other stock-related securities of the largest company in a particular country included in the S&P Developed ex-U.S. Small Cap Index ranged from approximately $410 million (Argentina) to $14.4 billion (Switzerland) (based on exchange rates as of May 31, 2016). As of May 31, 2016, the publicly traded market capitalization of the largest small company (as defined by the Fund) ranged from approximately $519 million (Egypt) to $17.6 billion (Switzerland) (based on exchange rates as of May 31, 2016). Under normal circumstances, the Fund invests directly and indirectly (e.g., through underlying funds or derivatives) at least 80% of its assets in securities of small companies that are tied economically to countries other than the United States, including both developed and emerging countries (see "Name Policies"). GMO selects investments using value-based fundamental analysis that is informed by a disciplined quantitative screening process. GMO analyzes companies for financial, operational, and managerial strength and compares them to their global, regional, and industry peers. GMO also considers a company's accounting and governance practices. As part of the investment process, GMO frequently meets with management and visits companies. The factors GMO considers and investment methods GMO uses can change over time. In pursuing its investment objective, the Fund may (but is not obligated to) invest in a wide variety of exchange-traded and over-the-counter (OTC) derivatives, including, without limitation, forward currency contracts, futures and options, as well as exchange-traded funds (ETFs). The Fund's foreign currency exposure may differ from the currency exposure of its equity investments. In addition, the Fund may lend its portfolio securities. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 31.25% (2Q2009) Lowest Quarter: – 24.05% (3Q2008) Year-to-Date (as of 3/31/16): – 1.83%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Foreign Small Companies Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.50%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.50%
Management fee	rr_ManagementFeesOverAssets	0.70%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.07%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.92%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.06%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.86%	[2]
1 Year	rr_ExpenseExampleYear01	$ 189
3 Years	rr_ExpenseExampleYear03	392
5 Years	rr_ExpenseExampleYear05	612
10 Years	rr_ExpenseExampleYear10	1,244
1 Year	rr_ExpenseExampleNoRedemptionYear01	137
3 Years	rr_ExpenseExampleNoRedemptionYear03	336
5 Years	rr_ExpenseExampleNoRedemptionYear05	551
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,170
2006	rr_AnnualReturn2006	35.83%
2007	rr_AnnualReturn2007	7.85%
2008	rr_AnnualReturn2008	(44.68%)
2009	rr_AnnualReturn2009	44.58%
2010	rr_AnnualReturn2010	24.83%
2011	rr_AnnualReturn2011	(15.25%)
2012	rr_AnnualReturn2012	22.57%
2013	rr_AnnualReturn2013	28.25%
2014	rr_AnnualReturn2014	(10.17%)
2015	rr_AnnualReturn2015	6.18%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(1.83%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	31.25%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(24.05%)
1 Year	rr_AverageAnnualReturnYear01	5.12%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05	4.70%	[3],[4]
10 Years	rr_AverageAnnualReturnYear10	6.29%	[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception	10.34%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 04, 1995	[3],[4]
GMO Foreign Small Companies Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.50%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.50%
Management fee	rr_ManagementFeesOverAssets	0.70%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.07%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.87%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.06%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.81%	[2]
1 Year	rr_ExpenseExampleYear01	$ 184
3 Years	rr_ExpenseExampleYear03	376
5 Years	rr_ExpenseExampleYear05	585
10 Years	rr_ExpenseExampleYear10	1,186
1 Year	rr_ExpenseExampleNoRedemptionYear01	132
3 Years	rr_ExpenseExampleNoRedemptionYear03	320
5 Years	rr_ExpenseExampleNoRedemptionYear05	524
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,112
1 Year	rr_AverageAnnualReturnYear01	5.11%	[3],[5]
5 Years	rr_AverageAnnualReturnYear05	4.75%	[3],[5]
10 Years	rr_AverageAnnualReturnYear10	6.32%	[3],[5]
Incept.	rr_AverageAnnualReturnSinceInception	10.54%	[3],[5]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 14, 2002	[3],[5]
GMO Foreign Small Companies Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	3.97%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05	3.84%	[3],[4]
10 Years	rr_AverageAnnualReturnYear10	4.85%	[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception		[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 04, 1995	[3],[4]
GMO Foreign Small Companies Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.11%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05	3.74%	[3],[4]
10 Years	rr_AverageAnnualReturnYear10	5.15%	[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception		[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 04, 1995	[3],[4]
GMO Foreign Small Companies Fund | S&P Developed ex-U.S. Small Cap Index (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.92%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05	5.51%	[3],[4]
10 Years	rr_AverageAnnualReturnYear10	5.33%	[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception	6.94%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 04, 1995	[3],[4]
GMO Foreign Small Companies Fund | S&P Developed ex-U.S. Small Cap Index (reflects no deduction for fees, expenses, or taxes) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.92%	[3],[5]
5 Years	rr_AverageAnnualReturnYear05	5.51%	[3],[5]
10 Years	rr_AverageAnnualReturnYear10	5.33%	[3],[5]
Incept.	rr_AverageAnnualReturnSinceInception	9.73%	[3],[5]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 14, 2002	[3],[5]

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

[3] Information on the Fund's return after taxes is unavailable prior to June 30, 2000, the date the Fund commenced operations as a registered investment company. Prior to that date, the Fund operated as a private investment pool with investment objectives, policies, and guidelines that were substantially the same as those of the Fund.

[4] Performance of Class III shares prior to June 30, 2000 is that of the private investment pool, restated to reflect the Fund's higher annual operating expenses. The pool was not registered as an investment company and therefore was not subject to certain restrictions imposed on the Fund by the Investment Company Act of 1940, as amended, and the Internal Revenue Code of 1986, as amended. Had the pool been subject to these restrictions, its performance may have been adversely affected.

[5] For the period from March 16, 2009 to August 12, 2009, no Class IV shares were outstanding. The returns shown in the table for that period are those of Class III shares, which have higher expenses.

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GMO International Small Companies Fund

GMO INTERNATIONAL SMALL COMPANIES FUND

Investment objective

Total return in excess of that of its benchmark, the S&P Developed ex-U.S. Small Cap Index.

Fees and expenses

The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees	GMO International Small Companies Fund Class III
Purchase premium (as a percentage of amount invested)	0.50%
Redemption fee (as a percentage of amount redeemed)	0.50%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO International Small Companies Fund Class III
Management fee	0.60%	[1]
Shareholder service fee	0.15%	[1]
Other expenses	0.19%
Total annual fund operating expenses	0.94%
Expense reimbursement/waiver	(0.18%)	[1]
Total annual fund operating expenses	0.76%	[2]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO International Small Companies Fund | Class III | USD ($)	179	386	611	1,257

If you do not sell your shares

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO International Small Companies Fund | Class III | USD ($)	127	330	550	1,183

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 64% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 49% of the average value of its portfolio.

Principal investment strategies

The Fund typically invests directly and indirectly in equities of companies tied economically to countries other than the United States whose outstanding publicly traded equities are in the lowest 25% of publicly traded market capitalization (float) in a particular country at the time of investment ("small companies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The market capitalization range of companies whose equities are held by the Fund is generally within the market capitalization range of companies in the Fund's benchmark, which represents the lowest 15% of publicly traded market capitalization (float) of the S&P Broad Market Index in each country. Depending on the country, as of May 31, 2016, the market capitalization of the outstanding common stock and other stock-related securities of the largest company in a particular country included in the S&P Developed ex-U.S. Small Cap Index ranged from approximately $410 million (Argentina) to $14.4 billion (Switzerland) (based on exchange rates as of May 31, 2016). As of May 31, 2016, the publicly traded market capitalization of the largest small company (as defined by the Fund) ranged from approximately $519 million (Egypt) to $17.6 billion (Switzerland) (based on exchange rates as of May 31, 2016). Under normal circumstances, the Fund invests directly and indirectly (e.g., through underlying funds or derivatives) at least 80% of its assets in securities of small companies that are tied economically to countries other than the United States, including both developed and emerging countries (see "Name Policies").

GMO selects investments using value-based fundamental analysis that is informed by a disciplined quantitative screening process. GMO analyzes companies for financial, operational, and managerial strength and compares them to their global, regional, and industry peers. GMO also considers a company's accounting and governance practices. As part of the investment process, GMO frequently meets with management and visits companies.

The factors GMO considers and investment methods GMO uses can change over time.

In pursuing its investment objective, the Fund may (but is not obligated to) invest in a wide variety of exchange-traded and over-the-counter (OTC) derivatives, including, without limitation, forward currency contracts, futures and options, as well as exchange-traded funds (ETFs). The Fund's foreign currency exposure may differ from the currency exposure of its equity investments. In addition, the Fund may lend its portfolio securities.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund's shares changes with the value of the Fund's investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see "Description of Principal Risks."

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund's foreign currency holdings and investments denominated in foreign currencies.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund's investments.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin or otherwise honor its obligations.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of two broad-based indices (including the Fund’s benchmark) and a composite index computed by GMO. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance. The Fund was managed by a different investment team pursuant to a different investment objective and strategy prior to May 1, 2016 (i.e., during the periods covered by the performance information shown below), which materially reduces the relevance of the performance results shown below.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 32.07% (2Q2009)
Lowest Quarter: – 21.36% (3Q2011)
Year-to-Date (as of 3/31/16): 0.85%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO International Small Companies Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class III		0.76%	5.48%	5.25%	8.97%	Oct. 14, 1991
Class III | Return After Taxes on Distributions		0.36%	3.38%	2.75%	6.70%	Oct. 14, 1991
Class III | Return After Taxes on Distributions and Sale of Fund Shares		1.05%	4.13%	4.11%	7.19%	Oct. 14, 1991
S&P Developed ex-U.S. Small Cap Index (Fund benchmark) (reflects no deduction for fees, expenses, or taxes)	[1]	5.92%	5.51%	5.33%	6.74%	Oct. 14, 1991
S&P Developed ex-U.S. Small Cap + Index (Composite index)		9.59%	6.32%	6.01%	7.02%	Oct. 14, 1991
MSCI EAFE Small Cap Index (Prior Fund benchmark) (returns reflect no deductions for fees or expenses, but are net of withholding tax on dividend reinvestments)	[1]	9.59%	6.32%	4.55%		Oct. 14, 1991

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund’s management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund’s direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[2] after expense reimbursement/waiver

[1] Effective May 1, 2016, the Fund changed its benchmark from the MSCI EAFE Small Cap Index to the S&P Developed ex-U.S. Small Cap Index because GMO believes the S&P Developed ex-U.S. Small Cap Index is a more appropriate comparative, broad-based market index for the Fund in light of changes to the Fund's investment objective and principal investment strategies.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO International Small Companies Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO INTERNATIONAL SMALL COMPANIES FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the S&P Developed ex-U.S. Small Cap Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 64% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 49% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	64.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund typically invests directly and indirectly in equities of companies tied economically to countries other than the United States whose outstanding publicly traded equities are in the lowest 25% of publicly traded market capitalization (float) in a particular country at the time of investment ("small companies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The market capitalization range of companies whose equities are held by the Fund is generally within the market capitalization range of companies in the Fund's benchmark, which represents the lowest 15% of publicly traded market capitalization (float) of the S&P Broad Market Index in each country. Depending on the country, as of May 31, 2016, the market capitalization of the outstanding common stock and other stock-related securities of the largest company in a particular country included in the S&P Developed ex-U.S. Small Cap Index ranged from approximately $410 million (Argentina) to $14.4 billion (Switzerland) (based on exchange rates as of May 31, 2016). As of May 31, 2016, the publicly traded market capitalization of the largest small company (as defined by the Fund) ranged from approximately $519 million (Egypt) to $17.6 billion (Switzerland) (based on exchange rates as of May 31, 2016). Under normal circumstances, the Fund invests directly and indirectly (e.g., through underlying funds or derivatives) at least 80% of its assets in securities of small companies that are tied economically to countries other than the United States, including both developed and emerging countries (see "Name Policies"). GMO selects investments using value-based fundamental analysis that is informed by a disciplined quantitative screening process. GMO analyzes companies for financial, operational, and managerial strength and compares them to their global, regional, and industry peers. GMO also considers a company's accounting and governance practices. As part of the investment process, GMO frequently meets with management and visits companies. The factors GMO considers and investment methods GMO uses can change over time. In pursuing its investment objective, the Fund may (but is not obligated to) invest in a wide variety of exchange-traded and over-the-counter (OTC) derivatives, including, without limitation, forward currency contracts, futures and options, as well as exchange-traded funds (ETFs). The Fund's foreign currency exposure may differ from the currency exposure of its equity investments. In addition, the Fund may lend its portfolio securities. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund's shares changes with the value of the Fund's investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see "Description of Principal Risks." Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund's foreign currency holdings and investments denominated in foreign currencies. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund's investments. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin or otherwise honor its obligations. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of two broad-based indices (including the Fund’s benchmark) and a composite index computed by GMO. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance. The Fund was managed by a different investment team pursuant to a different investment objective and strategy prior to May 1, 2016 (i.e., during the periods covered by the performance information shown below), which materially reduces the relevance of the performance results shown below.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of two broad-based indices (including the Fund’s benchmark) and a composite index computed by GMO.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 32.07% (2Q2009) Lowest Quarter: – 21.36% (3Q2011) Year-to-Date (as of 3/31/16): 0.85%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Market Index Changed	rr_PerformanceTableMarketIndexChanged	Effective May 1, 2016, the Fund changed its benchmark from the MSCI EAFE Small Cap Index to the S&P Developed ex-U.S. Small Cap Index because GMO believes the S&P Developed ex-U.S. Small Cap Index is a more appropriate comparative, broad-based market index for the Fund in light of changes to the Fund's investment objective and principal investment strategies.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO International Small Companies Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.50%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.50%
Management fee	rr_ManagementFeesOverAssets	0.60%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.19%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.94%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.18%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.76%	[2]
1 Year	rr_ExpenseExampleYear01	$ 179
3 Years	rr_ExpenseExampleYear03	386
5 Years	rr_ExpenseExampleYear05	611
10 Years	rr_ExpenseExampleYear10	1,257
1 Year	rr_ExpenseExampleNoRedemptionYear01	127
3 Years	rr_ExpenseExampleNoRedemptionYear03	330
5 Years	rr_ExpenseExampleNoRedemptionYear05	550
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,183
2006	rr_AnnualReturn2006	27.36%
2007	rr_AnnualReturn2007	7.63%
2008	rr_AnnualReturn2008	(42.37%)
2009	rr_AnnualReturn2009	33.44%
2010	rr_AnnualReturn2010	21.18%
2011	rr_AnnualReturn2011	(14.55%)
2012	rr_AnnualReturn2012	23.98%
2013	rr_AnnualReturn2013	31.45%
2014	rr_AnnualReturn2014	(6.98%)
2015	rr_AnnualReturn2015	1.78%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.85%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	32.07%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(21.36%)
1 Year	rr_AverageAnnualReturnYear01	0.76%
5 Years	rr_AverageAnnualReturnYear05	5.48%
10 Years	rr_AverageAnnualReturnYear10	5.25%
Incept.	rr_AverageAnnualReturnSinceInception	8.97%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 14, 1991
GMO International Small Companies Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.36%
5 Years	rr_AverageAnnualReturnYear05	3.38%
10 Years	rr_AverageAnnualReturnYear10	2.75%
Incept.	rr_AverageAnnualReturnSinceInception	6.70%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 14, 1991
GMO International Small Companies Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.05%
5 Years	rr_AverageAnnualReturnYear05	4.13%
10 Years	rr_AverageAnnualReturnYear10	4.11%
Incept.	rr_AverageAnnualReturnSinceInception	7.19%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 14, 1991
GMO International Small Companies Fund | S&P Developed ex-U.S. Small Cap Index (Fund benchmark) (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.92%	[3]
5 Years	rr_AverageAnnualReturnYear05	5.51%	[3]
10 Years	rr_AverageAnnualReturnYear10	5.33%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	6.74%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 14, 1991	[3]
GMO International Small Companies Fund | S&P Developed ex-U.S. Small Cap + Index (Composite index)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	9.59%
5 Years	rr_AverageAnnualReturnYear05	6.32%
10 Years	rr_AverageAnnualReturnYear10	6.01%
Incept.	rr_AverageAnnualReturnSinceInception	7.02%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 14, 1991
GMO International Small Companies Fund | MSCI EAFE Small Cap Index (Prior Fund benchmark) (returns reflect no deductions for fees or expenses, but are net of withholding tax on dividend reinvestments)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	9.59%	[3]
5 Years	rr_AverageAnnualReturnYear05	6.32%	[3]
10 Years	rr_AverageAnnualReturnYear10	4.55%	[3]
Incept.	rr_AverageAnnualReturnSinceInception		[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 14, 1991	[3]

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund’s management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund’s direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[2] after expense reimbursement/waiver

[3] Effective May 1, 2016, the Fund changed its benchmark from the MSCI EAFE Small Cap Index to the S&P Developed ex-U.S. Small Cap Index because GMO believes the S&P Developed ex-U.S. Small Cap Index is a more appropriate comparative, broad-based market index for the Fund in light of changes to the Fund's investment objective and principal investment strategies.

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GMO U.S. Equity Allocation Fund

GMO U.S. EQUITY ALLOCATION FUND

Investment objective

High total return.

Fees and expenses

The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO U.S. Equity Allocation Fund		Class III	Class IV	Class V	Class VI
Management fee	[1]	0.31%	0.31%	0.31%	0.31%
Shareholder service fee	[1]	0.15%	0.10%	0.085%	0.055%
Other expenses		0.02%	0.02%	0.02%	0.02%
Total annual fund operating expenses		0.48%	0.43%	0.42%	0.39%
Expense reimbursement/waiver	[1]	(0.02%)	(0.02%)	(0.02%)	(0.02%)
Total annual fund operating expenses	[2]	0.46%	0.41%	0.40%	0.37%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - GMO U.S. Equity Allocation Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	47	152	267	602
Class IV	42	136	239	540
Class V	41	133	233	528
Class VI	38	123	217	491

Expense Example, No Redemption - GMO U.S. Equity Allocation Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	47	152	267	602
Class IV	42	136	239	540
Class V	41	133	233	528
Class VI	38	123	217	491

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 89% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 63% of the average value of its portfolio.

Principal investment strategies

GMO seeks to achieve the Fund's investment objective by investing primarily in a portfolio of equities in U.S. equity markets. GMO selects the securities the Fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, the overall global economy, and governmental policies.

In selecting securities for the Fund, GMO uses a combination of investment methods to identify securities that GMO believes have positive return potential relative to other securities in U.S. equity markets. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to U.S. equity markets. GMO also uses its multi-year return forecasts for asset classes and other groups of securities in its investment process and may adjust the Fund's portfolio based on factors such as position size, industry and sector exposure, and market capitalization. At times, the Fund may have substantial exposure to a single industry, sector or market capitalization. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark.

As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, and swap contracts. In addition, the Fund may lend its portfolio securities.

Under normal circumstances, the Fund invests directly and indirectly (e.g., through underlying funds or derivatives) at least 80% of its assets in equities tied economically to the United States (see "Name Policies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Focused Investment Risk – Investments focused in sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 11.90% (3Q2010)
Lowest Quarter: – 16.34% (4Q2008)
Year-to-Date (as of 3/31/16): 2.22%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO U.S. Equity Allocation Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	[1]	0.65%	11.69%	5.93%	10.90%	Sep. 18, 1985
Class III | Return After Taxes on Distributions	[1]	(2.20%)	10.05%	4.74%	8.28%	Sep. 18, 1985
Class III | Return After Taxes on Distributions and Sale of Fund Shares	[1]	2.62%	9.30%	4.71%	8.31%	Sep. 18, 1985
Class III | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)	[1]	1.38%	12.57%	7.31%	10.86%	Sep. 18, 1985
Class IV	[1]	0.67%	11.74%	5.98%	6.24%	Jan. 09, 1998
Class IV | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)	[1]	1.38%	12.57%	7.31%	6.45%	Jan. 09, 1998
Class VI	[1]	0.70%	11.78%	6.03%	7.02%	Jun. 30, 2003
Class VI | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)	[1]	1.38%	12.57%	7.31%	8.30%	Jun. 30, 2003

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

[1] The Fund is the successor to GMO U.S. Core Fund, a former series of GMO Trust that had an investment objective and investment policies and restrictions substantially identical to those of the Fund. Performance of the Fund through September 16, 2005 is that of GMO U.S. Core Fund and reflects GMO U.S. Core Fund's annual operating expenses (0.02% higher than those of the Fund). As of the date of this Prospectus, no Class V shares of the Fund or its predecessor have been outstanding since February 11, 2005. Class V shares would be invested in the same portfolio of securities as Class III shares. Annual returns would principally differ to the extent Class V shares do not have the same expenses as Class III shares.

[1] The Fund is the successor to GMO U.S. Core Fund, a former series of GMO Trust that had an investment objective and investment policies and restrictions substantially identical to those of the Fund. Performance of the Fund through September 16, 2005 is that of GMO U.S. Core Fund and reflects GMO U.S. Core Fund's annual operating expenses (0.02% higher than those of the Fund). As of the date of this Prospectus, no Class V shares of the Fund or its predecessor have been outstanding since February 11, 2005. Class V shares would be invested in the same portfolio of securities as Class III shares. Annual returns would principally differ to the extent Class V shares do not have the same expenses as Class III shares.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO U.S. Equity Allocation Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO U.S. EQUITY ALLOCATION FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	High total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 89% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 63% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	89.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO seeks to achieve the Fund's investment objective by investing primarily in a portfolio of equities in U.S. equity markets. GMO selects the securities the Fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, the overall global economy, and governmental policies. In selecting securities for the Fund, GMO uses a combination of investment methods to identify securities that GMO believes have positive return potential relative to other securities in U.S. equity markets. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to U.S. equity markets. GMO also uses its multi-year return forecasts for asset classes and other groups of securities in its investment process and may adjust the Fund's portfolio based on factors such as position size, industry and sector exposure, and market capitalization. At times, the Fund may have substantial exposure to a single industry, sector or market capitalization. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include futures, options, and swap contracts. In addition, the Fund may lend its portfolio securities. Under normal circumstances, the Fund invests directly and indirectly (e.g., through underlying funds or derivatives) at least 80% of its assets in equities tied economically to the United States (see "Name Policies"). The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Focused Investment Risk – Investments focused in sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 11.90% (3Q2010) Lowest Quarter: – 16.34% (4Q2008) Year-to-Date (as of 3/31/16): 2.22%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO U.S. Equity Allocation Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.31%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.48%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.46%	[2]
1 Year	rr_ExpenseExampleYear01	$ 47
3 Years	rr_ExpenseExampleYear03	152
5 Years	rr_ExpenseExampleYear05	267
10 Years	rr_ExpenseExampleYear10	602
1 Year	rr_ExpenseExampleNoRedemptionYear01	47
3 Years	rr_ExpenseExampleNoRedemptionYear03	152
5 Years	rr_ExpenseExampleNoRedemptionYear05	267
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 602
2006	rr_AnnualReturn2006	9.57%	[3]
2007	rr_AnnualReturn2007	1.57%	[3]
2008	rr_AnnualReturn2008	(30.29%)	[3]
2009	rr_AnnualReturn2009	21.23%	[3]
2010	rr_AnnualReturn2010	8.82%	[3]
2011	rr_AnnualReturn2011	8.07%	[3]
2012	rr_AnnualReturn2012	12.81%	[3]
2013	rr_AnnualReturn2013	29.61%	[3]
2014	rr_AnnualReturn2014	9.27%	[3]
2015	rr_AnnualReturn2015	0.65%	[3]
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	2.22%	[3]
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2010
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	11.90%	[3]
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(16.34%)	[3]
1 Year	rr_AverageAnnualReturnYear01	0.65%	[3]
5 Years	rr_AverageAnnualReturnYear05	11.69%	[3]
10 Years	rr_AverageAnnualReturnYear10	5.93%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	10.90%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 18, 1985	[3]
GMO U.S. Equity Allocation Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.31%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.43%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.41%	[2]
1 Year	rr_ExpenseExampleYear01	$ 42
3 Years	rr_ExpenseExampleYear03	136
5 Years	rr_ExpenseExampleYear05	239
10 Years	rr_ExpenseExampleYear10	540
1 Year	rr_ExpenseExampleNoRedemptionYear01	42
3 Years	rr_ExpenseExampleNoRedemptionYear03	136
5 Years	rr_ExpenseExampleNoRedemptionYear05	239
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 540
1 Year	rr_AverageAnnualReturnYear01	0.67%	[3]
5 Years	rr_AverageAnnualReturnYear05	11.74%	[3]
10 Years	rr_AverageAnnualReturnYear10	5.98%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	6.24%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998	[3]
GMO U.S. Equity Allocation Fund | Class V
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.31%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.085%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.42%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.40%	[2]
1 Year	rr_ExpenseExampleYear01	$ 41
3 Years	rr_ExpenseExampleYear03	133
5 Years	rr_ExpenseExampleYear05	233
10 Years	rr_ExpenseExampleYear10	528
1 Year	rr_ExpenseExampleNoRedemptionYear01	41
3 Years	rr_ExpenseExampleNoRedemptionYear03	133
5 Years	rr_ExpenseExampleNoRedemptionYear05	233
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 528
GMO U.S. Equity Allocation Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.31%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.39%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.37%	[2]
1 Year	rr_ExpenseExampleYear01	$ 38
3 Years	rr_ExpenseExampleYear03	123
5 Years	rr_ExpenseExampleYear05	217
10 Years	rr_ExpenseExampleYear10	491
1 Year	rr_ExpenseExampleNoRedemptionYear01	38
3 Years	rr_ExpenseExampleNoRedemptionYear03	123
5 Years	rr_ExpenseExampleNoRedemptionYear05	217
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 491
1 Year	rr_AverageAnnualReturnYear01	0.70%	[3]
5 Years	rr_AverageAnnualReturnYear05	11.78%	[3]
10 Years	rr_AverageAnnualReturnYear10	6.03%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	7.02%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 30, 2003	[3]
GMO U.S. Equity Allocation Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.20%)	[3]
5 Years	rr_AverageAnnualReturnYear05	10.05%	[3]
10 Years	rr_AverageAnnualReturnYear10	4.74%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	8.28%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 18, 1985	[3]
GMO U.S. Equity Allocation Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	2.62%	[3]
5 Years	rr_AverageAnnualReturnYear05	9.30%	[3]
10 Years	rr_AverageAnnualReturnYear10	4.71%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	8.31%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 18, 1985	[3]
GMO U.S. Equity Allocation Fund | S&P 500 Index (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.38%	[3]
5 Years	rr_AverageAnnualReturnYear05	12.57%	[3]
10 Years	rr_AverageAnnualReturnYear10	7.31%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	10.86%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 18, 1985	[3]
GMO U.S. Equity Allocation Fund | S&P 500 Index (reflects no deduction for fees, expenses, or taxes) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.38%	[3]
5 Years	rr_AverageAnnualReturnYear05	12.57%	[3]
10 Years	rr_AverageAnnualReturnYear10	7.31%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	6.45%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998	[3]
GMO U.S. Equity Allocation Fund | S&P 500 Index (reflects no deduction for fees, expenses, or taxes) | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.38%	[3]
5 Years	rr_AverageAnnualReturnYear05	12.57%	[3]
10 Years	rr_AverageAnnualReturnYear10	7.31%	[3]
Incept.	rr_AverageAnnualReturnSinceInception	8.30%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 30, 2003	[3]

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

[3] The Fund is the successor to GMO U.S. Core Fund, a former series of GMO Trust that had an investment objective and investment policies and restrictions substantially identical to those of the Fund. Performance of the Fund through September 16, 2005 is that of GMO U.S. Core Fund and reflects GMO U.S. Core Fund's annual operating expenses (0.02% higher than those of the Fund). As of the date of this Prospectus, no Class V shares of the Fund or its predecessor have been outstanding since February 11, 2005. Class V shares would be invested in the same portfolio of securities as Class III shares. Annual returns would principally differ to the extent Class V shares do not have the same expenses as Class III shares.

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GMO Emerging Markets Fund

GMO EMERGING MARKETS FUND

Investment objective

Total return in excess of that of its benchmark, the S&P/IFCI Composite Index.

Fees and expenses

The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees - GMO Emerging Markets Fund	Class II		Class III		Class IV		Class V		Class VI
Purchase premium (as a percentage of amount invested)	0.80%		0.80%		0.80%		0.80%		0.80%
Redemption fee (as a percentage of amount redeemed)	0.80%	[1]	0.80%	[1]	0.80%	[1]	0.80%	[1]	0.80%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Emerging Markets Fund		Class II	Class III	Class IV	Class V	Class VI
Management fee	[1]	0.75%	0.75%	0.75%	0.75%	0.75%
Shareholder service fee	[1]	0.22%	0.15%	0.105%	0.085%	0.055%
Other expenses		0.14%	0.15%	0.14%	0.15%	0.15%
Acquired fund fees and expenses (underlying fund expenses)	[2]	0.02%	0.02%	0.02%	0.02%	0.02%
Total annual fund operating expenses		1.13%	1.07%	1.02%	1.01%	0.98%
Expense reimbursement/waiver	[1]	(0.03%)	(0.01%)	(0.01%)	(0.04%)	(0.04%)
Total annual fund operating expenses	[3]	1.10%	1.06%	1.01%	0.97%	0.94%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example - GMO Emerging Markets Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class II	274	522	790	1,557
Class III	270	506	761	1,491
Class IV	265	490	734	1,434
Class V	261	484	726	1,420
Class VI	258	475	710	1,386

If you do not sell your shares

Expense Example, No Redemption - GMO Emerging Markets Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class II	191	433	694	1,441
Class III	187	417	664	1,374
Class IV	182	401	638	1,317
Class V	178	395	630	1,303
Class VI	175	386	613	1,268

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 104% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 76% of the average value of its portfolio.

Principal investment strategies

The Fund typically invests directly and indirectly (e.g., through underlying funds or derivatives) in equities of companies tied economically to emerging markets. "Emerging markets" include all markets that are not treated as "developed markets" in the MSCI World Index or MSCI EAFE Index. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in investments tied economically to emerging markets (see "Name Policies"). In addition to investing in companies tied economically to emerging markets, the Fund may invest in companies that GMO believes are likely to benefit from growth in the emerging markets. GMO expects that the Fund will have a value bias relative to its benchmark.

GMO uses proprietary quantitative techniques and fundamental analysis to evaluate and select countries, sectors, and equity investments based on factors including, but not limited to, valuation and macroeconomic factors. In constructing the Fund's portfolio, GMO weighs a number of factors, including the trade-off among forecasted returns, risk relative to the benchmark, transaction costs, and liquidity. GMO also adjusts the Fund's portfolio for factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time.

As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund's foreign currency exposure may differ from the currency exposure represented by its equity investments. In addition, the Fund may overweight and underweight its positions in particular currencies relative to its benchmark. In addition, the Fund may lend its portfolio securities.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Focused Investment Risk – Investments focused in a limited number of countries and regions (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests (including ETFs), including the risk that those underlying funds will not perform as expected.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 31.90% (2Q2009)
Lowest Quarter: – 30.50% (4Q2008)
Year-to-Date (as of 3/31/16): 9.14%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Emerging Markets Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class II	[1]	(17.53%)	(6.91%)	1.32%	6.66%	Nov. 29, 1996
Class II | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes)	[1]	(12.38%)	(3.68%)	4.73%	6.32%	Nov. 29, 1996
Class III		(17.49%)	(6.85%)	1.38%	6.46%	Dec. 09, 1993
Class III | Return After Taxes on Distributions		(18.02%)	(7.53%)	(0.23%)	5.09%	Dec. 09, 1993
Class III | Return After Taxes on Distributions and Sale of Fund Shares		(9.23%)	(4.37%)	2.22%	5.83%	Dec. 09, 1993
Class III | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes)		(12.38%)	(3.68%)	4.73%	5.33%	Dec. 09, 1993
Class IV		(17.41%)	(6.81%)	1.42%	7.84%	Jan. 09, 1998
Class IV | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes)		(12.38%)	(3.68%)	4.73%	8.30%	Jan. 09, 1998
Class V	[2]	(17.48%)	(6.79%)	1.45%	8.73%	Aug. 04, 2003
Class V | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes)	[2]	(12.38%)	(3.68%)	4.73%	10.64%	Aug. 04, 2003
Class VI		(17.42%)	(6.75%)	1.49%	9.04%	Jun. 30, 2003
Class VI | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes)		(12.38%)	(3.68%)	4.73%	11.01%	Jun. 30, 2003

[1] Applies only to shares acquired on or after June 1, 1995 (including shares acquired by reinvestment of dividends or other distribution). With respect to Class III shares purchased through third-party intermediaries and any shares acquired prior to March 27, 2002, the level of redemption fee charged by the Fund is 0.40%.

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses and state and federal registration fees. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. In addition, GMO has contractually agreed to waive the shareholder service fees charged to each class of shares of the Fund to the extent necessary to prevent the shareholder service fees paid by the class from exceeding the following amounts of the class's average daily net assets: 0.20% for Class II shares, 0.15% for Class III shares, 0.10% for Class IV shares, 0.05% for Class V shares, and 0.02% for Class VI shares. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] These indirect expenses include commissions paid to brokers by the Fund for executing transactions in unaffiliated underlying funds ("transaction fees"). Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.01% and 0.01%, respectively.

[3] after expense reimbursement/waiver (Fund and underlying fund expenses)

[1] For the period from January 9, 1998 to August 12, 2009, no Class II shares were outstanding. The returns shown in the table for that period are those of Class III shares, which have been adjusted downward to reflect Class II's higher total annual fund operating expenses (Class II's expenses during these periods were calculated by adjusting Class III's actual total annual fund operating expenses during such periods upward by the current differential between "Total annual fund operating expenses" for Class II and Class III shares shown in the Fund's "Annual Fund operating expenses" table).

[2] For the period from October 26, 2004 to February 11, 2005, no Class V shares were outstanding. The returns shown in the table for that period are those of Class IV shares, which have higher expenses.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Emerging Markets Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO EMERGING MARKETS FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the S&P/IFCI Composite Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 104% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 76% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	104.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund typically invests directly and indirectly (e.g., through underlying funds or derivatives) in equities of companies tied economically to emerging markets. "Emerging markets" include all markets that are not treated as "developed markets" in the MSCI World Index or MSCI EAFE Index. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in investments tied economically to emerging markets (see "Name Policies"). In addition to investing in companies tied economically to emerging markets, the Fund may invest in companies that GMO believes are likely to benefit from growth in the emerging markets. GMO expects that the Fund will have a value bias relative to its benchmark. GMO uses proprietary quantitative techniques and fundamental analysis to evaluate and select countries, sectors, and equity investments based on factors including, but not limited to, valuation and macroeconomic factors. In constructing the Fund's portfolio, GMO weighs a number of factors, including the trade-off among forecasted returns, risk relative to the benchmark, transaction costs, and liquidity. GMO also adjusts the Fund's portfolio for factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund's foreign currency exposure may differ from the currency exposure represented by its equity investments. In addition, the Fund may overweight and underweight its positions in particular currencies relative to its benchmark. In addition, the Fund may lend its portfolio securities. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Focused Investment Risk – Investments focused in a limited number of countries and regions (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests (including ETFs), including the risk that those underlying funds will not perform as expected. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 31.90% (2Q2009) Lowest Quarter: – 30.50% (4Q2008) Year-to-Date (as of 3/31/16): 9.14%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Emerging Markets Fund | Class II
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.80%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.80%	[1]
Management fee	rr_ManagementFeesOverAssets	0.75%	[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.22%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.13%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.03%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.10%	[4]
1 Year	rr_ExpenseExampleYear01	$ 274
3 Years	rr_ExpenseExampleYear03	522
5 Years	rr_ExpenseExampleYear05	790
10 Years	rr_ExpenseExampleYear10	1,557
1 Year	rr_ExpenseExampleNoRedemptionYear01	191
3 Years	rr_ExpenseExampleNoRedemptionYear03	433
5 Years	rr_ExpenseExampleNoRedemptionYear05	694
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,441
1 Year	rr_AverageAnnualReturnYear01	(17.53%)	[5]
5 Years	rr_AverageAnnualReturnYear05	(6.91%)	[5]
10 Years	rr_AverageAnnualReturnYear10	1.32%	[5]
Incept.	rr_AverageAnnualReturnSinceInception	6.66%	[5]
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 29, 1996	[5]
GMO Emerging Markets Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.80%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.80%	[1]
Management fee	rr_ManagementFeesOverAssets	0.75%	[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.15%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.07%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.06%	[4]
1 Year	rr_ExpenseExampleYear01	$ 270
3 Years	rr_ExpenseExampleYear03	506
5 Years	rr_ExpenseExampleYear05	761
10 Years	rr_ExpenseExampleYear10	1,491
1 Year	rr_ExpenseExampleNoRedemptionYear01	187
3 Years	rr_ExpenseExampleNoRedemptionYear03	417
5 Years	rr_ExpenseExampleNoRedemptionYear05	664
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,374
2006	rr_AnnualReturn2006	29.72%
2007	rr_AnnualReturn2007	36.58%
2008	rr_AnnualReturn2008	(55.10%)
2009	rr_AnnualReturn2009	70.59%
2010	rr_AnnualReturn2010	20.51%
2011	rr_AnnualReturn2011	(17.10%)
2012	rr_AnnualReturn2012	16.21%
2013	rr_AnnualReturn2013	(5.86%)
2014	rr_AnnualReturn2014	(6.29%)
2015	rr_AnnualReturn2015	(16.15%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	9.14%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	31.90%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(30.50%)
1 Year	rr_AverageAnnualReturnYear01	(17.49%)
5 Years	rr_AverageAnnualReturnYear05	(6.85%)
10 Years	rr_AverageAnnualReturnYear10	1.38%
Incept.	rr_AverageAnnualReturnSinceInception	6.46%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 09, 1993
GMO Emerging Markets Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.80%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.80%	[1]
Management fee	rr_ManagementFeesOverAssets	0.75%	[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.105%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.02%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.01%	[4]
1 Year	rr_ExpenseExampleYear01	$ 265
3 Years	rr_ExpenseExampleYear03	490
5 Years	rr_ExpenseExampleYear05	734
10 Years	rr_ExpenseExampleYear10	1,434
1 Year	rr_ExpenseExampleNoRedemptionYear01	182
3 Years	rr_ExpenseExampleNoRedemptionYear03	401
5 Years	rr_ExpenseExampleNoRedemptionYear05	638
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,317
1 Year	rr_AverageAnnualReturnYear01	(17.41%)
5 Years	rr_AverageAnnualReturnYear05	(6.81%)
10 Years	rr_AverageAnnualReturnYear10	1.42%
Incept.	rr_AverageAnnualReturnSinceInception	7.84%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998
GMO Emerging Markets Fund | Class V
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.80%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.80%	[1]
Management fee	rr_ManagementFeesOverAssets	0.75%	[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.085%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.15%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.01%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.97%	[4]
1 Year	rr_ExpenseExampleYear01	$ 261
3 Years	rr_ExpenseExampleYear03	484
5 Years	rr_ExpenseExampleYear05	726
10 Years	rr_ExpenseExampleYear10	1,420
1 Year	rr_ExpenseExampleNoRedemptionYear01	178
3 Years	rr_ExpenseExampleNoRedemptionYear03	395
5 Years	rr_ExpenseExampleNoRedemptionYear05	630
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,303
1 Year	rr_AverageAnnualReturnYear01	(17.48%)	[6]
5 Years	rr_AverageAnnualReturnYear05	(6.79%)	[6]
10 Years	rr_AverageAnnualReturnYear10	1.45%	[6]
Incept.	rr_AverageAnnualReturnSinceInception	8.73%	[6]
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 04, 2003	[6]
GMO Emerging Markets Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.80%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.80%
Management fee	rr_ManagementFeesOverAssets	0.75%	[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.15%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.98%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.94%	[4]
1 Year	rr_ExpenseExampleYear01	$ 258
3 Years	rr_ExpenseExampleYear03	475
5 Years	rr_ExpenseExampleYear05	710
10 Years	rr_ExpenseExampleYear10	1,386
1 Year	rr_ExpenseExampleNoRedemptionYear01	175
3 Years	rr_ExpenseExampleNoRedemptionYear03	386
5 Years	rr_ExpenseExampleNoRedemptionYear05	613
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,268
1 Year	rr_AverageAnnualReturnYear01	(17.42%)
5 Years	rr_AverageAnnualReturnYear05	(6.75%)
10 Years	rr_AverageAnnualReturnYear10	1.49%
Incept.	rr_AverageAnnualReturnSinceInception	9.04%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 30, 2003
GMO Emerging Markets Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(18.02%)
5 Years	rr_AverageAnnualReturnYear05	(7.53%)
10 Years	rr_AverageAnnualReturnYear10	(0.23%)
Incept.	rr_AverageAnnualReturnSinceInception	5.09%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 09, 1993
GMO Emerging Markets Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(9.23%)
5 Years	rr_AverageAnnualReturnYear05	(4.37%)
10 Years	rr_AverageAnnualReturnYear10	2.22%
Incept.	rr_AverageAnnualReturnSinceInception	5.83%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 09, 1993
GMO Emerging Markets Fund | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes) | Class II
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(12.38%)	[5]
5 Years	rr_AverageAnnualReturnYear05	(3.68%)	[5]
10 Years	rr_AverageAnnualReturnYear10	4.73%	[5]
Incept.	rr_AverageAnnualReturnSinceInception	6.32%	[5]
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 29, 1996	[5]
GMO Emerging Markets Fund | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(12.38%)
5 Years	rr_AverageAnnualReturnYear05	(3.68%)
10 Years	rr_AverageAnnualReturnYear10	4.73%
Incept.	rr_AverageAnnualReturnSinceInception	5.33%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 09, 1993
GMO Emerging Markets Fund | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(12.38%)
5 Years	rr_AverageAnnualReturnYear05	(3.68%)
10 Years	rr_AverageAnnualReturnYear10	4.73%
Incept.	rr_AverageAnnualReturnSinceInception	8.30%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998
GMO Emerging Markets Fund | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes) | Class V
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(12.38%)	[6]
5 Years	rr_AverageAnnualReturnYear05	(3.68%)	[6]
10 Years	rr_AverageAnnualReturnYear10	4.73%	[6]
Incept.	rr_AverageAnnualReturnSinceInception	10.64%	[6]
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 04, 2003	[6]
GMO Emerging Markets Fund | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes) | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(12.38%)
5 Years	rr_AverageAnnualReturnYear05	(3.68%)
10 Years	rr_AverageAnnualReturnYear10	4.73%
Incept.	rr_AverageAnnualReturnSinceInception	11.01%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 30, 2003

[1] Applies only to shares acquired on or after June 1, 1995 (including shares acquired by reinvestment of dividends or other distribution). With respect to Class III shares purchased through third-party intermediaries and any shares acquired prior to March 27, 2002, the level of redemption fee charged by the Fund is 0.40%.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses and state and federal registration fees. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. In addition, GMO has contractually agreed to waive the shareholder service fees charged to each class of shares of the Fund to the extent necessary to prevent the shareholder service fees paid by the class from exceeding the following amounts of the class's average daily net assets: 0.20% for Class II shares, 0.15% for Class III shares, 0.10% for Class IV shares, 0.05% for Class V shares, and 0.02% for Class VI shares. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] These indirect expenses include commissions paid to brokers by the Fund for executing transactions in unaffiliated underlying funds ("transaction fees"). Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.01% and 0.01%, respectively.

[4] after expense reimbursement/waiver (Fund and underlying fund expenses)

[5] For the period from January 9, 1998 to August 12, 2009, no Class II shares were outstanding. The returns shown in the table for that period are those of Class III shares, which have been adjusted downward to reflect Class II's higher total annual fund operating expenses (Class II's expenses during these periods were calculated by adjusting Class III's actual total annual fund operating expenses during such periods upward by the current differential between "Total annual fund operating expenses" for Class II and Class III shares shown in the Fund's "Annual Fund operating expenses" table).

[6] For the period from October 26, 2004 to February 11, 2005, no Class V shares were outstanding. The returns shown in the table for that period are those of Class IV shares, which have higher expenses.

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GMO Emerging Countries Fund

GMO EMERGING COUNTRIES FUND

Investment objective

Total return in excess of that of its benchmark, the S&P/IFCI Composite Index.

Fees and expenses

The table below describes the fees and expenses that you may bear if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Emerging Countries Fund Class III
Management fee	0.65%	[1]
Shareholder service fee	0.15%	[1]
Other expenses	1.28%
Acquired fund fees and expenses (underlying fund expenses)	0.02%	[2]
Total annual fund operating expenses	2.10%
Expense reimbursement/waiver	(0.77%)	[1]
Total annual fund operating expenses	1.33%	[3]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amount shown reflects the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Emerging Countries Fund | Class III | USD ($)	135	584	1,058	2,370

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Emerging Countries Fund | Class III | USD ($)	135	584	1,058	2,370

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 59% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 57% of the average value of its portfolio.

Principal investment strategies

The Fund typically invests directly and indirectly (e.g., through underlying funds or derivatives) in equities of companies tied economically to emerging countries. "Emerging countries" include all countries that are not treated as "developed market countries" in the MSCI World Index or MSCI EAFE Index. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in investments tied economically to emerging countries (see "Name Policies"). In addition to investing in companies tied economically to emerging countries, the Fund may invest in companies that GMO believes are likely to benefit from growth in the emerging markets. GMO expects that the Fund will have a value bias relative to its benchmark. In general, the Fund typically invests in companies with larger market capitalizations than does Emerging Markets Fund.

GMO uses proprietary quantitative techniques and fundamental analysis to evaluate and select countries, sectors, and equity investments based on factors including, but not limited to, valuation and macroeconomic factors. In constructing the Fund's portfolio, GMO weighs a number of factors, including the trade-off among forecasted returns, risk relative to the benchmark, transaction costs, and liquidity. GMO also adjusts the Fund's portfolio for factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time.

As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund's foreign currency exposure may differ from the currency exposure represented by its equity investments. In addition, the Fund may overweight and underweight its positions in particular currencies relative to its benchmark. In addition, the Fund may lend its portfolio securities.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Focused Investment Risk – Investments focused in a limited number of countries and regions (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests (including ETFs), including the risk that those underlying funds will not perform as expected.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 31.14% (2Q2009)
Lowest Quarter: – 31.38% (4Q2008)
Year-to-Date (as of 3/31/16): 9.34%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Emerging Countries Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(15.19%)	(6.73%)	1.40%	6.30%	Aug. 29, 1997
Class III | Return After Taxes on Distributions	(15.71%)	(7.01%)	(0.10%)	4.98%	Aug. 29, 1997
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(7.50%)	(4.51%)	2.26%	5.90%	Aug. 29, 1997
S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes)	(12.38%)	(3.68%)	4.73%	6.42%	Aug. 29, 1997

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the portion of its "Specified Operating Expenses" (as defined below) that exceeds 0.35% of the Fund's average daily net assets. "Specified Operating Expenses" means only the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] These indirect expenses include commissions paid to brokers by the Fund for executing transactions in unaffiliated underlying funds ("transaction fees"). Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were 0.02% and less than 0.01%, respectively.

[3] after expense reimbursement/waiver (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Emerging Countries Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO EMERGING COUNTRIES FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the S&P/IFCI Composite Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 59% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 57% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	59.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amount shown reflects the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund typically invests directly and indirectly (e.g., through underlying funds or derivatives) in equities of companies tied economically to emerging countries. "Emerging countries" include all countries that are not treated as "developed market countries" in the MSCI World Index or MSCI EAFE Index. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in investments tied economically to emerging countries (see "Name Policies"). In addition to investing in companies tied economically to emerging countries, the Fund may invest in companies that GMO believes are likely to benefit from growth in the emerging markets. GMO expects that the Fund will have a value bias relative to its benchmark. In general, the Fund typically invests in companies with larger market capitalizations than does Emerging Markets Fund. GMO uses proprietary quantitative techniques and fundamental analysis to evaluate and select countries, sectors, and equity investments based on factors including, but not limited to, valuation and macroeconomic factors. In constructing the Fund's portfolio, GMO weighs a number of factors, including the trade-off among forecasted returns, risk relative to the benchmark, transaction costs, and liquidity. GMO also adjusts the Fund's portfolio for factors such as position size, market capitalization, and exposure to particular industries, sectors, countries, regions, or currencies. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund's foreign currency exposure may differ from the currency exposure represented by its equity investments. In addition, the Fund may overweight and underweight its positions in particular currencies relative to its benchmark. In addition, the Fund may lend its portfolio securities. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Focused Investment Risk – Investments focused in a limited number of countries and regions (or in sectors within a country or region) that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests (including ETFs), including the risk that those underlying funds will not perform as expected. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 31.14% (2Q2009) Lowest Quarter: – 31.38% (4Q2008) Year-to-Date (as of 3/31/16): 9.34%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Emerging Countries Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.65%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	1.28%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	2.10%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.77%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.33%	[3]
1 Year	rr_ExpenseExampleYear01	$ 135
3 Years	rr_ExpenseExampleYear03	584
5 Years	rr_ExpenseExampleYear05	1,058
10 Years	rr_ExpenseExampleYear10	2,370
1 Year	rr_ExpenseExampleNoRedemptionYear01	135
3 Years	rr_ExpenseExampleNoRedemptionYear03	584
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,058
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,370
2006	rr_AnnualReturn2006	29.52%
2007	rr_AnnualReturn2007	37.78%
2008	rr_AnnualReturn2008	(54.93%)
2009	rr_AnnualReturn2009	68.01%
2010	rr_AnnualReturn2010	20.47%
2011	rr_AnnualReturn2011	(17.16%)
2012	rr_AnnualReturn2012	15.09%
2013	rr_AnnualReturn2013	(6.56%)
2014	rr_AnnualReturn2014	(6.59%)
2015	rr_AnnualReturn2015	(15.19%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	9.34%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	31.14%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(31.38%)
1 Year	rr_AverageAnnualReturnYear01	(15.19%)
5 Years	rr_AverageAnnualReturnYear05	(6.73%)
10 Years	rr_AverageAnnualReturnYear10	1.40%
Incept.	rr_AverageAnnualReturnSinceInception	6.30%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 29, 1997
GMO Emerging Countries Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(15.71%)
5 Years	rr_AverageAnnualReturnYear05	(7.01%)
10 Years	rr_AverageAnnualReturnYear10	(0.10%)
Incept.	rr_AverageAnnualReturnSinceInception	4.98%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 29, 1997
GMO Emerging Countries Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(7.50%)
5 Years	rr_AverageAnnualReturnYear05	(4.51%)
10 Years	rr_AverageAnnualReturnYear10	2.26%
Incept.	rr_AverageAnnualReturnSinceInception	5.90%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 29, 1997
GMO Emerging Countries Fund | S&P/IFCI Composite Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(12.38%)
5 Years	rr_AverageAnnualReturnYear05	(3.68%)
10 Years	rr_AverageAnnualReturnYear10	4.73%
Incept.	rr_AverageAnnualReturnSinceInception	6.42%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 29, 1997

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the portion of its "Specified Operating Expenses" (as defined below) that exceeds 0.35% of the Fund's average daily net assets. "Specified Operating Expenses" means only the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] These indirect expenses include commissions paid to brokers by the Fund for executing transactions in unaffiliated underlying funds ("transaction fees"). Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were 0.02% and less than 0.01%, respectively.

[3] after expense reimbursement/waiver (Fund and underlying fund expenses)

XML

GMO Emerging Domestic Opportunities Fund

GMO EMERGING DOMESTIC OPPORTUNITIES FUND

Investment objective

Total return.

Fees and expenses

The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees - GMO Emerging Domestic Opportunities Fund	Class II	Class III	Class IV	Class V	Class VI
Purchase premium (as a percentage of amount invested)	0.80%	0.80%	0.80%	0.80%	0.80%
Redemption fee (as a percentage of amount redeemed)	0.80%	0.80%	0.80%	0.80%	0.80%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Emerging Domestic Opportunities Fund		Class II	Class III	Class IV	Class V	Class VI
Management fee	[1]	0.75%	0.75%	0.75%	0.75%	0.75%
Shareholder service fee	[1]	0.22%	0.15%	0.105%	0.085%	0.055%
Other expenses		0.14%	0.14%	0.14%	0.14%	0.14%
Acquired fund fees and expenses (underlying fund expenses)	[2]	0.11%	0.11%	0.11%	0.11%	0.11%
Total annual fund operating expenses		1.22%	1.15%	1.11%	1.09%	1.06%
Expense reimbursement/waiver	[1]	(0.04%)	(0.04%)	(0.04%)	(0.04%)	(0.04%)
Total annual fund operating expenses	[3]	1.18%	1.11%	1.07%	1.05%	1.02%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example - GMO Emerging Domestic Opportunities Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class II	282	549	837	1,657
Class III	275	527	800	1,579
Class IV	271	515	779	1,534
Class V	269	509	768	1,511
Class VI	266	500	753	1,477

If you do not sell your shares

Expense Example, No Redemption - GMO Emerging Domestic Opportunities Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class II	199	460	741	1,542
Class III	192	439	704	1,463
Class IV	188	426	683	1,417
Class V	186	420	672	1,395
Class VI	183	411	656	1,360

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 250% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 189% of the average value of its portfolio.

Principal investment strategies

The Fund typically invests directly and indirectly (e.g., through underlying funds or derivatives) in equities, and, to a lesser extent, fixed income securities, of companies whose prospects are linked to the internal ("domestic") development and growth of the world's non-developed markets ("emerging markets"), including companies that provide goods and services to emerging market consumers. "Emerging markets" include all markets that are not treated as "developed markets" in the MSCI World Index or MSCI EAFE Index.

The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in investments related to emerging markets (see "Name Policies"). The Fund's investments are not limited to investments in companies located in any particular country or geographic region, and often include investments in companies located in developed markets (e.g., the United States) that are related to, or whose prospects are linked to, emerging markets. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark.

GMO primarily uses fundamental analysis to evaluate and select countries, sectors, and companies that it believes are likely to benefit from domestic growth in emerging markets. The process begins with country and sector allocation and then focuses on the selection of individual companies. In evaluating and selecting investments, GMO may consider many factors, including, among others, GMO's assessment of a country's and/or sector's fundamentals or growth prospects as well as a company's positioning relative to its competitors. In constructing the Fund's portfolio, GMO weighs a number of factors, including the trade-off among forecasted returns, risk, transaction costs, and liquidity. The factors GMO considers and investment methods GMO uses can change over time.

As an alternative to investing directly in equities and fixed income securities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund's foreign currency exposure may differ from the currency exposure represented by its equity investments. In addition, the Fund may lend its portfolio securities.

The Fund may invest in securities of companies of any market capitalization. The Fund also may invest in securities of any credit quality (including below investment grade securities (commonly referred to as "junk bonds")).

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market's uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer's, guarantor's, or obligor's failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin or otherwise honor its obligations.

• Focused Investment Risk – The Fund's investments in companies whose prospects are linked to the internal development and growth of a particular emerging markets country create additional risk because the performance of those companies is likely to be highly correlated.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests (including ETFs), including the risk that those underlying funds will not perform as expected.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class II shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class II Shares
Years Ending December 31

Highest Quarter: 12.66% (1Q2012)
Lowest Quarter: – 10.52% (3Q2015)
Year-to-Date (as of 3/31/16): 1.49%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Emerging Domestic Opportunities Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class II	(9.76%)			1.60%	Mar. 24, 2011
Class II | Return After Taxes on Distributions	(9.81%)			1.24%	Mar. 24, 2011
Class II | Return After Taxes on Distributions and Sale of Fund Shares	(4.88%)			1.39%	Mar. 24, 2011
Class II | MSCI Emerging Markets Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(14.92%)			(4.80%)	Mar. 24, 2011
Class III	(9.73%)			1.94%	Jun. 29, 2012
Class III | MSCI Emerging Markets Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(14.92%)			(2.29%)	Jun. 29, 2012
Class IV	(9.69%)			0.64%	May 02, 2012
Class IV | MSCI Emerging Markets Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(14.92%)			(4.44%)	May 02, 2012
Class V	(9.62%)			(5.23%)	Nov. 29, 2013
Class V | MSCI Emerging Markets Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(14.92%)			(9.08%)	Nov. 29, 2013
Class VI	(9.63%)			2.61%	Sep. 19, 2011
Class VI | MSCI Emerging Markets Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(14.92%)			(1.72%)	Sep. 19, 2011

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and any portion of custody expenses that exceeds 0.10% of the Fund's average daily net assets. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] These indirect expenses include commissions paid to brokers by the Fund for executing transactions in unaffiliated underlying funds ("transaction fees"). Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.04% and 0.07%, respectively.

[3] after expense reimbursement/waiver (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Emerging Domestic Opportunities Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO EMERGING DOMESTIC OPPORTUNITIES FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 250% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 189% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	250.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund typically invests directly and indirectly (e.g., through underlying funds or derivatives) in equities, and, to a lesser extent, fixed income securities, of companies whose prospects are linked to the internal ("domestic") development and growth of the world's non-developed markets ("emerging markets"), including companies that provide goods and services to emerging market consumers. "Emerging markets" include all markets that are not treated as "developed markets" in the MSCI World Index or MSCI EAFE Index. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in investments related to emerging markets (see "Name Policies"). The Fund's investments are not limited to investments in companies located in any particular country or geographic region, and often include investments in companies located in developed markets (e.g., the United States) that are related to, or whose prospects are linked to, emerging markets. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. GMO primarily uses fundamental analysis to evaluate and select countries, sectors, and companies that it believes are likely to benefit from domestic growth in emerging markets. The process begins with country and sector allocation and then focuses on the selection of individual companies. In evaluating and selecting investments, GMO may consider many factors, including, among others, GMO's assessment of a country's and/or sector's fundamentals or growth prospects as well as a company's positioning relative to its competitors. In constructing the Fund's portfolio, GMO weighs a number of factors, including the trade-off among forecasted returns, risk, transaction costs, and liquidity. The factors GMO considers and investment methods GMO uses can change over time. As an alternative to investing directly in equities and fixed income securities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund's foreign currency exposure may differ from the currency exposure represented by its equity investments. In addition, the Fund may lend its portfolio securities. The Fund may invest in securities of companies of any market capitalization. The Fund also may invest in securities of any credit quality (including below investment grade securities (commonly referred to as "junk bonds")). The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market's uncertainty about the value of a fixed income investment (or class of fixed income investments). Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer's, guarantor's, or obligor's failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin or otherwise honor its obligations. Focused Investment Risk – The Fund's investments in companies whose prospects are linked to the internal development and growth of a particular emerging markets country create additional risk because the performance of those companies is likely to be highly correlated. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests (including ETFs), including the risk that those underlying funds will not perform as expected. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class II shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's annual total returns from year to year for the periods indicated and by comparing the Fund's average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class II Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 12.66% (1Q2012) Lowest Quarter: – 10.52% (3Q2015) Year-to-Date (as of 3/31/16): 1.49%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class II shares only; after-tax returns for other classes will vary.
GMO Emerging Domestic Opportunities Fund | Class II
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.80%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.80%
Management fee	rr_ManagementFeesOverAssets	0.75%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.22%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.11%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.22%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.18%	[3]
1 Year	rr_ExpenseExampleYear01	$ 282
3 Years	rr_ExpenseExampleYear03	549
5 Years	rr_ExpenseExampleYear05	837
10 Years	rr_ExpenseExampleYear10	1,657
1 Year	rr_ExpenseExampleNoRedemptionYear01	199
3 Years	rr_ExpenseExampleNoRedemptionYear03	460
5 Years	rr_ExpenseExampleNoRedemptionYear05	741
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,542
2012	rr_AnnualReturn2012	25.08%
2013	rr_AnnualReturn2013	3.40%
2014	rr_AnnualReturn2014	(0.69%)
2015	rr_AnnualReturn2015	(8.30%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	1.49%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	12.66%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(10.52%)
1 Year	rr_AverageAnnualReturnYear01	(9.76%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.60%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 24, 2011
GMO Emerging Domestic Opportunities Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.80%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.80%
Management fee	rr_ManagementFeesOverAssets	0.75%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.11%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.15%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.11%	[3]
1 Year	rr_ExpenseExampleYear01	$ 275
3 Years	rr_ExpenseExampleYear03	527
5 Years	rr_ExpenseExampleYear05	800
10 Years	rr_ExpenseExampleYear10	1,579
1 Year	rr_ExpenseExampleNoRedemptionYear01	192
3 Years	rr_ExpenseExampleNoRedemptionYear03	439
5 Years	rr_ExpenseExampleNoRedemptionYear05	704
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,463
1 Year	rr_AverageAnnualReturnYear01	(9.73%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.94%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 29, 2012
GMO Emerging Domestic Opportunities Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.80%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.80%
Management fee	rr_ManagementFeesOverAssets	0.75%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.105%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.11%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.11%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.07%	[3]
1 Year	rr_ExpenseExampleYear01	$ 271
3 Years	rr_ExpenseExampleYear03	515
5 Years	rr_ExpenseExampleYear05	779
10 Years	rr_ExpenseExampleYear10	1,534
1 Year	rr_ExpenseExampleNoRedemptionYear01	188
3 Years	rr_ExpenseExampleNoRedemptionYear03	426
5 Years	rr_ExpenseExampleNoRedemptionYear05	683
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,417
1 Year	rr_AverageAnnualReturnYear01	(9.69%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.64%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 02, 2012
GMO Emerging Domestic Opportunities Fund | Class V
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.80%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.80%
Management fee	rr_ManagementFeesOverAssets	0.75%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.085%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.11%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.09%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.05%	[3]
1 Year	rr_ExpenseExampleYear01	$ 269
3 Years	rr_ExpenseExampleYear03	509
5 Years	rr_ExpenseExampleYear05	768
10 Years	rr_ExpenseExampleYear10	1,511
1 Year	rr_ExpenseExampleNoRedemptionYear01	186
3 Years	rr_ExpenseExampleNoRedemptionYear03	420
5 Years	rr_ExpenseExampleNoRedemptionYear05	672
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,395
1 Year	rr_AverageAnnualReturnYear01	(9.62%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(5.23%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 29, 2013
GMO Emerging Domestic Opportunities Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.80%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.80%
Management fee	rr_ManagementFeesOverAssets	0.75%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.11%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.06%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.02%	[3]
1 Year	rr_ExpenseExampleYear01	$ 266
3 Years	rr_ExpenseExampleYear03	500
5 Years	rr_ExpenseExampleYear05	753
10 Years	rr_ExpenseExampleYear10	1,477
1 Year	rr_ExpenseExampleNoRedemptionYear01	183
3 Years	rr_ExpenseExampleNoRedemptionYear03	411
5 Years	rr_ExpenseExampleNoRedemptionYear05	656
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,360
1 Year	rr_AverageAnnualReturnYear01	(9.63%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	2.61%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 19, 2011
GMO Emerging Domestic Opportunities Fund | Return After Taxes on Distributions | Class II
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(9.81%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.24%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 24, 2011
GMO Emerging Domestic Opportunities Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class II
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(4.88%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 24, 2011
GMO Emerging Domestic Opportunities Fund | MSCI Emerging Markets Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class II
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(14.92%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(4.80%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 24, 2011
GMO Emerging Domestic Opportunities Fund | MSCI Emerging Markets Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(14.92%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(2.29%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 29, 2012
GMO Emerging Domestic Opportunities Fund | MSCI Emerging Markets Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(14.92%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(4.44%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 02, 2012
GMO Emerging Domestic Opportunities Fund | MSCI Emerging Markets Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class V
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(14.92%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(9.08%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 29, 2013
GMO Emerging Domestic Opportunities Fund | MSCI Emerging Markets Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(14.92%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(1.72%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 19, 2011

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and any portion of custody expenses that exceeds 0.10% of the Fund's average daily net assets. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] These indirect expenses include commissions paid to brokers by the Fund for executing transactions in unaffiliated underlying funds ("transaction fees"). Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.04% and 0.07%, respectively.

[3] after expense reimbursement/waiver (Fund and underlying fund expenses)

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GMO Global Bond Fund

GMO GLOBAL BOND FUND

Investment objective

Total return in excess of that of its benchmark, the J.P. Morgan GBI Global.

Fees and expenses

The table below describes the fees and expenses that you may bear if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Global Bond Fund Class III
Management fee	0.19%	[1]
Shareholder service fee	0.15%	[1]
Other expenses	1.00%	[2]
Acquired fund fees and expenses (underlying fund expenses)	0.05%	[3]
Total annual fund operating expenses	1.39%
Expense reimbursement/waiver	(0.93%)	[1]
Total annual fund operating expenses	0.46%	[4]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amount shown reflects the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Global Bond Fund | Class III | USD ($)	47	355	685	1,619

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Global Bond Fund | Class III | USD ($)	47	355	685	1,619

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 65% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 21% of the average value of its portfolio.

Principal investment strategies

The Fund's investment program has two principal components. One component seeks to replicate the Fund's benchmark. The second component seeks to add value relative to the Fund's benchmark by making investments that often will not track its benchmark. These investments principally include global interest rate and currency derivatives and indirect (through other GMO Funds) and direct credit investments in asset-backed, government and emerging country debt securities, and can cause the Fund's performance to differ significantly from that of its benchmark. The Fund typically has substantial direct and indirect investment exposure to the countries (e.g., Japan) and regions (e.g., Eurozone) that represent a significant portion of the Fund's benchmark.

In deciding what investments to make in global interest rate and currency markets and the size of those investments, GMO considers fundamental factors (e.g., inflation and current account positions) as well as price-based factors (e.g., interest and exchange rates). GMO evaluates the relative attractiveness of particular markets and instruments using various fixed income risk premium measures, which typically include exposure to term structure, foreign exchange, volatility, credit, liquidity and other risks. GMO also may consider the relative attractiveness of yield curve and duration positions in these markets.

In making decisions regarding credit investments, GMO uses fundamental investment techniques to assess the expected performance of each investment relative to the Fund's benchmark.

The factors GMO considers and investment methods GMO uses can change over time.

In pursuing its investment program, the Fund may make investments in:

• derivatives, including without limitation, futures contracts, currency options, interest rate options, currency forwards, reverse repurchase agreements, and swap contracts, such as credit default swaps, swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, variance swaps, commodity swaps, inflation swaps, municipal swaps, correlation swaps, and other types of swaps (to generate a return comparable to the Fund's benchmark and to generate return in global interest rate, currency, and credit markets);

• non-U.S. bonds and other bonds denominated in various currencies, including non-U.S. and U.S. government bonds, asset-backed securities issued by non-U.S. governments and U.S. government agencies (whether or not guaranteed or insured by those governments), corporate bonds, and mortgage-backed and other asset-backed securities issued by private issuers;

• shares of Debt Opportunities Fund (to provide exposure to credit (particularly, asset-backed) markets);

• shares of Emerging Country Debt Fund ("ECDF") (to provide exposure to emerging country debt securities); and

• shares of U.S. Treasury Fund, money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

As a result primarily of its investment in shares of Debt Opportunities Fund and ECDF, the Fund has and expects to continue to have material exposure to U.S. asset-backed and emerging country debt securities that are below investment grade (below investment grade debt investments are sometimes referred to as "junk bonds," although this term is not generally used to refer to emerging country debt securities).

GMO normally seeks to maintain the Fund's estimated interest rate duration within 2 years of the benchmark's duration (approximately 7.9 years as of 5/31/16). For an additional discussion of duration, see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Bond Funds — Duration."

Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in bonds (see "Name Policies"). The term "bond" includes (i) obligations of an issuer to make payments on future dates of principal, interest (whether fixed or variable) or both and (ii) synthetic debt instruments created by GMO by using derivatives (e.g., a futures contract, swap contract, currency forward, or option).

From time to time, the Fund may have some direct or indirect exposure to equities. The Fund may invest in securities of companies of any market capitalization.

The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

Principal risks of investing in the Fund

The value of the Fund's shares changes with the value of the Fund's investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see "Description of Principal Risks."

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund's foreign currency holdings and investments denominated in foreign currencies.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market's uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer's, guarantor's, or obligor's failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin or otherwise honor its obligations.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated, such as the Fund's investments in non-U.S. government bonds and asset-backed securities secured by different types of consumer debt (e.g., credit-card receivables, automobile loans, and home equity loans), are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund's investments.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 11.84% (3Q2009)
Lowest Quarter: – 12.70% (4Q2008)
Year-to-Date (as of 3/31/16): 5.28%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Global Bond Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(3.59%)	2.89%	4.07%	5.36%	Dec. 28, 1995
Class III | Return After Taxes on Distributions	(3.59%)	2.35%	2.58%	3.14%	Dec. 28, 1995
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(2.03%)	2.04%	2.58%	3.26%	Dec. 28, 1995
J.P. Morgan GBI Global (reflects no deduction for fees, expenses, or taxes)	(2.61%)	0.34%	3.79%	4.47%	Dec. 28, 1995

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the portion of its "Specified Operating Expenses" (as defined below) that exceeds 0.06% of the Fund's average daily net assets. "Specified Operating Expenses" means only the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] The amount includes interest expense incurred by the Fund as a result of entering into reverse repurchase agreements and/or margin on cleared swap contracts, if any. "Other expenses" (before addition of interest expense) and interest expense were approximately 0.99% and 0.01%, respectively.

[3] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.04%, less than 0.01%, and 0.01%, respectively.

[4] after expense reimbursement/waiver (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Global Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO GLOBAL BOND FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the J.P. Morgan GBI Global.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 65% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 21% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	65.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amount shown reflects the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund's investment program has two principal components. One component seeks to replicate the Fund's benchmark. The second component seeks to add value relative to the Fund's benchmark by making investments that often will not track its benchmark. These investments principally include global interest rate and currency derivatives and indirect (through other GMO Funds) and direct credit investments in asset-backed, government and emerging country debt securities, and can cause the Fund's performance to differ significantly from that of its benchmark. The Fund typically has substantial direct and indirect investment exposure to the countries (e.g., Japan) and regions (e.g., Eurozone) that represent a significant portion of the Fund's benchmark. In deciding what investments to make in global interest rate and currency markets and the size of those investments, GMO considers fundamental factors (e.g., inflation and current account positions) as well as price-based factors (e.g., interest and exchange rates). GMO evaluates the relative attractiveness of particular markets and instruments using various fixed income risk premium measures, which typically include exposure to term structure, foreign exchange, volatility, credit, liquidity and other risks. GMO also may consider the relative attractiveness of yield curve and duration positions in these markets. In making decisions regarding credit investments, GMO uses fundamental investment techniques to assess the expected performance of each investment relative to the Fund's benchmark. The factors GMO considers and investment methods GMO uses can change over time. In pursuing its investment program, the Fund may make investments in: derivatives, including without limitation, futures contracts, currency options, interest rate options, currency forwards, reverse repurchase agreements, and swap contracts, such as credit default swaps, swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, variance swaps, commodity swaps, inflation swaps, municipal swaps, correlation swaps, and other types of swaps (to generate a return comparable to the Fund's benchmark and to generate return in global interest rate, currency, and credit markets); non-U.S. bonds and other bonds denominated in various currencies, including non-U.S. and U.S. government bonds, asset-backed securities issued by non-U.S. governments and U.S. government agencies (whether or not guaranteed or insured by those governments), corporate bonds, and mortgage-backed and other asset-backed securities issued by private issuers; shares of Debt Opportunities Fund (to provide exposure to credit (particularly, asset-backed) markets); shares of Emerging Country Debt Fund ("ECDF") (to provide exposure to emerging country debt securities); and shares of U.S. Treasury Fund, money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds. As a result primarily of its investment in shares of Debt Opportunities Fund and ECDF, the Fund has and expects to continue to have material exposure to U.S. asset-backed and emerging country debt securities that are below investment grade (below investment grade debt investments are sometimes referred to as "junk bonds," although this term is not generally used to refer to emerging country debt securities). GMO normally seeks to maintain the Fund's estimated interest rate duration within 2 years of the benchmark's duration (approximately 7.9 years as of 5/31/16). For an additional discussion of duration, see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Bond Funds — Duration." Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in bonds (see "Name Policies"). The term "bond" includes (i) obligations of an issuer to make payments on future dates of principal, interest (whether fixed or variable) or both and (ii) synthetic debt instruments created by GMO by using derivatives (e.g., a futures contract, swap contract, currency forward, or option). From time to time, the Fund may have some direct or indirect exposure to equities. The Fund may invest in securities of companies of any market capitalization. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund's shares changes with the value of the Fund's investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see "Description of Principal Risks." Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund's foreign currency holdings and investments denominated in foreign currencies. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market's uncertainty about the value of a fixed income investment (or class of fixed income investments). Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer's, guarantor's, or obligor's failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin or otherwise honor its obligations. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated, such as the Fund's investments in non-U.S. government bonds and asset-backed securities secured by different types of consumer debt (e.g., credit-card receivables, automobile loans, and home equity loans), are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund's investments. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's annual total returns from year to year for the periods indicated and by comparing the Fund's average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 11.84% (3Q2009) Lowest Quarter: – 12.70% (4Q2008) Year-to-Date (as of 3/31/16): 5.28%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Global Bond Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.19%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	1.00%	[2]
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.05%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.39%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.93%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.46%	[4]
1 Year	rr_ExpenseExampleYear01	$ 47
3 Years	rr_ExpenseExampleYear03	355
5 Years	rr_ExpenseExampleYear05	685
10 Years	rr_ExpenseExampleYear10	1,619
1 Year	rr_ExpenseExampleNoRedemptionYear01	47
3 Years	rr_ExpenseExampleNoRedemptionYear03	355
5 Years	rr_ExpenseExampleNoRedemptionYear05	685
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,619
2006	rr_AnnualReturn2006	8.53%
2007	rr_AnnualReturn2007	2.76%
2008	rr_AnnualReturn2008	(15.70%)
2009	rr_AnnualReturn2009	20.45%
2010	rr_AnnualReturn2010	14.14%
2011	rr_AnnualReturn2011	8.47%
2012	rr_AnnualReturn2012	7.19%
2013	rr_AnnualReturn2013	(1.65%)
2014	rr_AnnualReturn2014	4.59%
2015	rr_AnnualReturn2015	(3.59%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	5.28%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	11.84%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(12.70%)
1 Year	rr_AverageAnnualReturnYear01	(3.59%)
5 Years	rr_AverageAnnualReturnYear05	2.89%
10 Years	rr_AverageAnnualReturnYear10	4.07%
Incept.	rr_AverageAnnualReturnSinceInception	5.36%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 1995
GMO Global Bond Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(3.59%)
5 Years	rr_AverageAnnualReturnYear05	2.35%
10 Years	rr_AverageAnnualReturnYear10	2.58%
Incept.	rr_AverageAnnualReturnSinceInception	3.14%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 1995
GMO Global Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.03%)
5 Years	rr_AverageAnnualReturnYear05	2.04%
10 Years	rr_AverageAnnualReturnYear10	2.58%
Incept.	rr_AverageAnnualReturnSinceInception	3.26%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 1995
GMO Global Bond Fund | J.P. Morgan GBI Global (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.61%)
5 Years	rr_AverageAnnualReturnYear05	0.34%
10 Years	rr_AverageAnnualReturnYear10	3.79%
Incept.	rr_AverageAnnualReturnSinceInception	4.47%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 1995

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the portion of its "Specified Operating Expenses" (as defined below) that exceeds 0.06% of the Fund's average daily net assets. "Specified Operating Expenses" means only the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] The amount includes interest expense incurred by the Fund as a result of entering into reverse repurchase agreements and/or margin on cleared swap contracts, if any. "Other expenses" (before addition of interest expense) and interest expense were approximately 0.99% and 0.01%, respectively.

[3] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.04%, less than 0.01%, and 0.01%, respectively.

[4] after expense reimbursement/waiver (Fund and underlying fund expenses)

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GMO Currency Hedged International Bond Fund

GMO CURRENCY HEDGED INTERNATIONAL BOND FUND

Investment objective

Total return in excess of that of its benchmark, the J.P. Morgan GBI Global ex Japan ex U.S. (Hedged).

Fees and expenses

The table below describes the fees and expenses that you may bear if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Currency Hedged International Bond Fund Class III
Management fee	0.25%	[1]
Shareholder service fee	0.15%	[1]
Other expenses	0.57%	[2]
Acquired fund fees and expenses (underlying fund expenses)	0.05%	[3]
Total annual fund operating expenses	1.02%
Expense reimbursement/waiver	(0.58%)	[1]
Total annual fund operating expenses	0.44%	[4]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amount shown reflects the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Currency Hedged International Bond Fund | Class III | USD ($)	45	273	520	1,227

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Currency Hedged International Bond Fund | Class III | USD ($)	45	273	520	1,227

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 69% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 24% of the average value of its portfolio.

Principal investment strategies

The Fund's investment program has two principal components. One component seeks to replicate the Fund's benchmark. The second component seeks to add value relative to the Fund's benchmark by making investments that often will not track its benchmark. These investments principally include global interest rate and currency derivatives and indirect (through other GMO Funds) and direct credit investments in asset-backed, government and emerging country debt securities, and can cause the Fund's performance to differ significantly from that of its benchmark. The Fund typically has substantial direct and indirect investment exposure to the countries (e.g., United Kingdom) and regions (e.g., Eurozone) that represent a significant portion of the Fund's benchmark.

In deciding what investments to make in global interest rate and currency markets and the size of those investments, GMO considers fundamental factors (e.g., inflation and current account positions) as well as price-based factors (e.g., interest and exchange rates). GMO evaluates the relative attractiveness of particular markets and instruments using various fixed income risk premium measures, which typically include exposure to term structure, foreign exchange, volatility, credit, liquidity and other risks. GMO also may consider the relative attractiveness of yield curve and duration positions in these markets.

In making decisions regarding credit investments, GMO uses fundamental investment techniques to assess the expected performance of each investment relative to the Fund's benchmark.

The factors GMO considers and investment methods GMO uses can change over time.

In pursuing its investment program, the Fund may make investments in:

• derivatives, including without limitation, futures contracts, currency options, interest rate options, currency forwards, reverse repurchase agreements, and swap contracts, such as credit default swaps, swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, variance swaps, commodity swaps, inflation swaps, municipal swaps, correlation swaps, and other types of swaps (to generate a return comparable to the Fund's benchmark and to generate return in global interest rate, currency, and credit markets);

• bonds denominated in various currencies, including non-U.S. and U.S. government bonds, asset-backed securities issued by non-U.S. governments and U.S. government agencies (whether or not guaranteed or insured by those governments), corporate bonds, and mortgage-backed and other asset-backed securities issued by private issuers;

• shares of Debt Opportunities Fund (to provide exposure to credit (particularly, asset-backed) markets);

• shares of Emerging Country Debt Fund ("ECDF") (to provide exposure to emerging country debt securities); and

• shares of U.S. Treasury Fund, money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

The Fund generally attempts to hedge at least 75% of its net foreign currency exposure into U.S. dollars.

As a result primarily of its investment in shares of Debt Opportunities Fund and ECDF, the Fund has and expects to continue to have material exposure to U.S. asset-backed and emerging country debt securities that are below investment grade (below investment grade debt investments are sometimes referred to as "junk bonds," although this term is not generally used to refer to emerging country debt securities).

GMO normally seeks to maintain the Fund's estimated interest rate duration within 2 years of the benchmark's duration (approximately 8.1 years as of 5/31/16). For an additional discussion of duration, see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Bond Funds — Duration."

Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in bonds (see "Name Policies"). The term "bond" includes (i) obligations of an issuer to make payments on future dates of principal, interest (whether fixed or variable) or both and (ii) synthetic debt instruments created by GMO by using derivatives (e.g., a futures contract, swap contract, currency forward, or option).

From time to time, the Fund may have some direct or indirect exposure to equities. The Fund may invest in securities of companies of any market capitalization.

The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

Principal risks of investing in the Fund

The value of the Fund's shares changes with the value of the Fund's investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see "Description of Principal Risks."

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market's uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer's, guarantor's, or obligor's failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin or otherwise honor its obligations.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated, such as the Fund's investments in non-U.S. government bonds and asset-backed securities secured by different types of consumer debt (e.g., credit-card receivables, automobile loans, and home equity loans), are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund's foreign currency holdings and investments denominated in foreign currencies.

• Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund's investments.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund’s benchmark (which is a broad-based index) and a composite index computed by GMO. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 8.23% (3Q2009)
Lowest Quarter: – 11.09% (4Q2008)
Year-to-Date (as of 3/31/16): 2.76%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Currency Hedged International Bond Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	0.47%	7.12%	4.75%	7.81%	Sep. 30, 1994
Class III | Return After Taxes on Distributions	(3.52%)	4.79%	2.84%	4.66%	Sep. 30, 1994
Class III | Return After Taxes on Distributions and Sale of Fund Shares	0.22%	4.52%	2.88%	4.76%	Sep. 30, 1994
J.P. Morgan GBI Global ex Japan ex U.S. (Hedged) (Fund benchmark) (reflects no deduction for fees, expenses, or taxes)	1.59%	5.81%	4.99%	6.76%	Sep. 30, 1994
J.P. Morgan GBI Global ex Japan ex U.S. (Hedged) + (Composite index)	1.59%	5.81%	4.99%	6.80%	Sep. 30, 1994

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] The amount includes interest expense incurred by the Fund as a result of entering into reverse repurchase agreements and/or margin on cleared swap contracts, if any. "Other expenses" (before addition of interest expense) and interest expense were approximately 0.56% and 0.01%, respectively.

[3] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.04%, less than 0.01% and 0.01%, respectively.

[4] after expense reimbursement/waiver (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Currency Hedged International Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO CURRENCY HEDGED INTERNATIONAL BOND FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the J.P. Morgan GBI Global ex Japan ex U.S. (Hedged).
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 69% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 24% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	69.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amount shown reflects the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund's investment program has two principal components. One component seeks to replicate the Fund's benchmark. The second component seeks to add value relative to the Fund's benchmark by making investments that often will not track its benchmark. These investments principally include global interest rate and currency derivatives and indirect (through other GMO Funds) and direct credit investments in asset-backed, government and emerging country debt securities, and can cause the Fund's performance to differ significantly from that of its benchmark. The Fund typically has substantial direct and indirect investment exposure to the countries (e.g., United Kingdom) and regions (e.g., Eurozone) that represent a significant portion of the Fund's benchmark. In deciding what investments to make in global interest rate and currency markets and the size of those investments, GMO considers fundamental factors (e.g., inflation and current account positions) as well as price-based factors (e.g., interest and exchange rates). GMO evaluates the relative attractiveness of particular markets and instruments using various fixed income risk premium measures, which typically include exposure to term structure, foreign exchange, volatility, credit, liquidity and other risks. GMO also may consider the relative attractiveness of yield curve and duration positions in these markets. In making decisions regarding credit investments, GMO uses fundamental investment techniques to assess the expected performance of each investment relative to the Fund's benchmark. The factors GMO considers and investment methods GMO uses can change over time. In pursuing its investment program, the Fund may make investments in: derivatives, including without limitation, futures contracts, currency options, interest rate options, currency forwards, reverse repurchase agreements, and swap contracts, such as credit default swaps, swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, variance swaps, commodity swaps, inflation swaps, municipal swaps, correlation swaps, and other types of swaps (to generate a return comparable to the Fund's benchmark and to generate return in global interest rate, currency, and credit markets); bonds denominated in various currencies, including non-U.S. and U.S. government bonds, asset-backed securities issued by non-U.S. governments and U.S. government agencies (whether or not guaranteed or insured by those governments), corporate bonds, and mortgage-backed and other asset-backed securities issued by private issuers; shares of Debt Opportunities Fund (to provide exposure to credit (particularly, asset-backed) markets); shares of Emerging Country Debt Fund ("ECDF") (to provide exposure to emerging country debt securities); and shares of U.S. Treasury Fund, money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds. The Fund generally attempts to hedge at least 75% of its net foreign currency exposure into U.S. dollars. As a result primarily of its investment in shares of Debt Opportunities Fund and ECDF, the Fund has and expects to continue to have material exposure to U.S. asset-backed and emerging country debt securities that are below investment grade (below investment grade debt investments are sometimes referred to as "junk bonds," although this term is not generally used to refer to emerging country debt securities). GMO normally seeks to maintain the Fund's estimated interest rate duration within 2 years of the benchmark's duration (approximately 8.1 years as of 5/31/16). For an additional discussion of duration, see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Bond Funds — Duration." Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in bonds (see "Name Policies"). The term "bond" includes (i) obligations of an issuer to make payments on future dates of principal, interest (whether fixed or variable) or both and (ii) synthetic debt instruments created by GMO by using derivatives (e.g., a futures contract, swap contract, currency forward, or option). From time to time, the Fund may have some direct or indirect exposure to equities. The Fund may invest in securities of companies of any market capitalization. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund's shares changes with the value of the Fund's investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see "Description of Principal Risks." Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market's uncertainty about the value of a fixed income investment (or class of fixed income investments). Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer's, guarantor's, or obligor's failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin or otherwise honor its obligations. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated, such as the Fund's investments in non-U.S. government bonds and asset-backed securities secured by different types of consumer debt (e.g., credit-card receivables, automobile loans, and home equity loans), are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund's foreign currency holdings and investments denominated in foreign currencies. Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund's investments. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund’s benchmark (which is a broad-based index) and a composite index computed by GMO. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's annual total returns from year to year for the periods indicated and by comparing the Fund's average annual total returns for different calendar periods with those of the Fund's benchmark (which is a broad-based index) and a composite index computed by GMO.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 8.23% (3Q2009) Lowest Quarter: – 11.09% (4Q2008) Year-to-Date (as of 3/31/16): 2.76%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Currency Hedged International Bond Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.25%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.57%	[2]
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.05%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.02%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.58%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.44%	[4]
1 Year	rr_ExpenseExampleYear01	$ 45
3 Years	rr_ExpenseExampleYear03	273
5 Years	rr_ExpenseExampleYear05	520
10 Years	rr_ExpenseExampleYear10	1,227
1 Year	rr_ExpenseExampleNoRedemptionYear01	45
3 Years	rr_ExpenseExampleNoRedemptionYear03	273
5 Years	rr_ExpenseExampleNoRedemptionYear05	520
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,227
2006	rr_AnnualReturn2006	2.45%
2007	rr_AnnualReturn2007	(4.00%)
2008	rr_AnnualReturn2008	(13.56%)
2009	rr_AnnualReturn2009	18.81%
2010	rr_AnnualReturn2010	11.70%
2011	rr_AnnualReturn2011	7.97%
2012	rr_AnnualReturn2012	11.34%
2013	rr_AnnualReturn2013	0.14%
2014	rr_AnnualReturn2014	16.59%
2015	rr_AnnualReturn2015	0.47%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	2.76%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	8.23%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(11.09%)
1 Year	rr_AverageAnnualReturnYear01	0.47%
5 Years	rr_AverageAnnualReturnYear05	7.12%
10 Years	rr_AverageAnnualReturnYear10	4.75%
Incept.	rr_AverageAnnualReturnSinceInception	7.81%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 30, 1994
GMO Currency Hedged International Bond Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(3.52%)
5 Years	rr_AverageAnnualReturnYear05	4.79%
10 Years	rr_AverageAnnualReturnYear10	2.84%
Incept.	rr_AverageAnnualReturnSinceInception	4.66%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 30, 1994
GMO Currency Hedged International Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.22%
5 Years	rr_AverageAnnualReturnYear05	4.52%
10 Years	rr_AverageAnnualReturnYear10	2.88%
Incept.	rr_AverageAnnualReturnSinceInception	4.76%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 30, 1994
GMO Currency Hedged International Bond Fund | J.P. Morgan GBI Global ex Japan ex U.S. (Hedged) (Fund benchmark) (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.59%
5 Years	rr_AverageAnnualReturnYear05	5.81%
10 Years	rr_AverageAnnualReturnYear10	4.99%
Incept.	rr_AverageAnnualReturnSinceInception	6.76%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 30, 1994
GMO Currency Hedged International Bond Fund | J.P. Morgan GBI Global ex Japan ex U.S. (Hedged) + (Composite index)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.59%
5 Years	rr_AverageAnnualReturnYear05	5.81%
10 Years	rr_AverageAnnualReturnYear10	4.99%
Incept.	rr_AverageAnnualReturnSinceInception	6.80%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 30, 1994

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] The amount includes interest expense incurred by the Fund as a result of entering into reverse repurchase agreements and/or margin on cleared swap contracts, if any. "Other expenses" (before addition of interest expense) and interest expense were approximately 0.56% and 0.01%, respectively.

[3] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.04%, less than 0.01% and 0.01%, respectively.

[4] after expense reimbursement/waiver (Fund and underlying fund expenses)

XML

GMO Core Plus Bond Fund

GMO CORE PLUS BOND FUND

Investment objective

Total return in excess of that of its benchmark, the Barclays U.S. Aggregate Index.

Fees and expenses

The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Core Plus Bond Fund		Class III	Class IV
Management fee	[1]	0.25%	0.25%
Shareholder service fee	[1]	0.15%	0.10%
Other expenses	[2]	0.17%	0.17%
Acquired fund fees and expenses (underlying fund expenses)	[3]	0.07%	0.07%
Total annual fund operating expenses		0.64%	0.59%
Expense reimbursement/waiver	[1]	(0.21%)	(0.21%)
Total annual fund operating expenses	[4]	0.43%	0.38%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - GMO Core Plus Bond Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	44	197	363	845
Class IV	39	181	335	785

Expense Example, No Redemption - GMO Core Plus Bond Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	44	197	363	845
Class IV	39	181	335	785

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 21% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 15% of the average value of its portfolio.

Principal investment strategies

The Fund's investment program has two principal components. One component seeks to replicate the Fund's benchmark. The second component seeks to add value relative to the Fund's benchmark by making investments that often will not track its benchmark. These investments principally include global interest rate and currency derivatives and indirect (through other GMO Funds) and direct credit investments in asset-backed, government and emerging country debt securities, and can cause the Fund's performance to differ significantly from that of its benchmark.

In deciding what investments to make in global interest rate and currency markets and the size of those investments, GMO considers fundamental factors (e.g., inflation and current account positions) as well as price-based factors (e.g., interest and exchange rates). GMO evaluates the relative attractiveness of particular markets and instruments using various fixed income risk premium measures, which typically include exposure to term structure, foreign exchange, volatility, credit, liquidity and other risks. GMO also may consider the relative attractiveness of yield curve and duration positions in these markets.

In making decisions regarding credit investments, GMO uses fundamental investment techniques to assess the expected performance of each investment relative to the Fund's benchmark.

The factors GMO considers and investment methods GMO uses can change over time.

In pursuing its investment program, the Fund may make investments in:

• derivatives and short sales, including without limitation, futures contracts, currency options, interest rate options, currency forwards, reverse repurchase agreements, and swap contracts, such as credit default swaps, swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, variance swaps, commodity swaps, inflation swaps, municipal swaps, correlation swaps, and other types of swaps (to generate a return comparable to the Fund's benchmark and to generate return in global interest rate, currency, and credit markets);

• bonds denominated in various currencies, including non-U.S. and U.S. government bonds, asset-backed securities issued by non-U.S. governments and U.S. government agencies (whether or not guaranteed or insured by those governments), corporate bonds, and mortgage-backed and other asset-backed securities issued by private issuers;

• shares of Debt Opportunities Fund (to provide exposure to credit (particularly, asset-backed) markets);

• shares of Emerging Country Debt Fund ("ECDF") (to provide exposure to emerging country debt securities); and

• shares of U.S. Treasury Fund, money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

As a result primarily of its investment in shares of Debt Opportunities Fund and ECDF, the Fund has and expects to continue to have material exposure to U.S. asset-backed and emerging country debt securities that are below investment grade (below investment grade debt investments are sometimes referred to as "junk bonds," although this term is not generally used to refer to emerging country debt securities).

GMO normally seeks to maintain the Fund's estimated interest rate duration within 2 years of the benchmark's duration (approximately 5.5 years as of 5/31/16). For an additional discussion of duration, see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Bond Funds — Duration."

Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in bonds (see "Name Policies"). The term "bond" includes (i) obligations of an issuer to make payments on future dates of principal, interest (whether fixed or variable) or both and (ii) synthetic debt instruments created by GMO by using derivatives (e.g., a futures contract, swap contract, currency forward, or option).

From time to time, the Fund may have some direct or indirect exposure to equities. The Fund may invest in securities of companies of any market capitalization.

The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

Principal risks of investing in the Fund

The value of the Fund's shares changes with the value of the Fund's investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see "Description of Principal Risks."

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market's uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer's, guarantor's, or obligor's failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin or otherwise honor its obligations.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated, such as the Fund's investments in non-U.S. government bonds and asset-backed securities secured by different types of consumer debt (e.g., credit-card receivables, automobile loans, and home equity loans), are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund's foreign currency holdings and investments denominated in foreign currencies.

• Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund's investments.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 9.12% (3Q2009)
Lowest Quarter: – 15.24% (4Q2008)
Year-to-Date (as of 3/31/16): 1.12%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Core Plus Bond Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(1.55%)	5.33%	4.11%	5.54%	Apr. 30, 1997
Class III | Return After Taxes on Distributions	(3.67%)	3.24%	1.30%	2.88%	Apr. 30, 1997
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(0.87%)	3.27%	1.97%	3.21%	Apr. 30, 1997
Class III | Barclays U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes)	0.55%	3.25%	4.52%	5.47%	Apr. 30, 1997
Class IV	(1.40%)	5.38%	4.15%	4.18%	Jul. 26, 2005
Class IV | Barclays U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes)	0.55%	3.25%	4.52%	4.40%	Jul. 26, 2005

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] The amount includes interest expense incurred by the Fund as a result of entering into reverse repurchase agreements and/or margin on cleared swap contracts, if any. "Other expenses" (before addition of interest expense) and interest expense were approximately 0.16% and 0.01%, respectively.

[3] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.06%, less than 0.01% and 0.01%, respectively.

[4] after expense reimbursement/waiver (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Core Plus Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO CORE PLUS BOND FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the Barclays U.S. Aggregate Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 21% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 15% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	21.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund's investment program has two principal components. One component seeks to replicate the Fund's benchmark. The second component seeks to add value relative to the Fund's benchmark by making investments that often will not track its benchmark. These investments principally include global interest rate and currency derivatives and indirect (through other GMO Funds) and direct credit investments in asset-backed, government and emerging country debt securities, and can cause the Fund's performance to differ significantly from that of its benchmark. In deciding what investments to make in global interest rate and currency markets and the size of those investments, GMO considers fundamental factors (e.g., inflation and current account positions) as well as price-based factors (e.g., interest and exchange rates). GMO evaluates the relative attractiveness of particular markets and instruments using various fixed income risk premium measures, which typically include exposure to term structure, foreign exchange, volatility, credit, liquidity and other risks. GMO also may consider the relative attractiveness of yield curve and duration positions in these markets. In making decisions regarding credit investments, GMO uses fundamental investment techniques to assess the expected performance of each investment relative to the Fund's benchmark. The factors GMO considers and investment methods GMO uses can change over time. In pursuing its investment program, the Fund may make investments in: derivatives and short sales, including without limitation, futures contracts, currency options, interest rate options, currency forwards, reverse repurchase agreements, and swap contracts, such as credit default swaps, swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, variance swaps, commodity swaps, inflation swaps, municipal swaps, correlation swaps, and other types of swaps (to generate a return comparable to the Fund's benchmark and to generate return in global interest rate, currency, and credit markets); bonds denominated in various currencies, including non-U.S. and U.S. government bonds, asset-backed securities issued by non-U.S. governments and U.S. government agencies (whether or not guaranteed or insured by those governments), corporate bonds, and mortgage-backed and other asset-backed securities issued by private issuers; shares of Debt Opportunities Fund (to provide exposure to credit (particularly, asset-backed) markets); shares of Emerging Country Debt Fund ("ECDF") (to provide exposure to emerging country debt securities); and shares of U.S. Treasury Fund, money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds. As a result primarily of its investment in shares of Debt Opportunities Fund and ECDF, the Fund has and expects to continue to have material exposure to U.S. asset-backed and emerging country debt securities that are below investment grade (below investment grade debt investments are sometimes referred to as "junk bonds," although this term is not generally used to refer to emerging country debt securities). GMO normally seeks to maintain the Fund's estimated interest rate duration within 2 years of the benchmark's duration (approximately 5.5 years as of 5/31/16). For an additional discussion of duration, see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Bond Funds — Duration." Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in bonds (see "Name Policies"). The term "bond" includes (i) obligations of an issuer to make payments on future dates of principal, interest (whether fixed or variable) or both and (ii) synthetic debt instruments created by GMO by using derivatives (e.g., a futures contract, swap contract, currency forward, or option). From time to time, the Fund may have some direct or indirect exposure to equities. The Fund may invest in securities of companies of any market capitalization. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund's shares changes with the value of the Fund's investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see "Description of Principal Risks." Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market's uncertainty about the value of a fixed income investment (or class of fixed income investments). Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer's, guarantor's, or obligor's failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin or otherwise honor its obligations. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated, such as the Fund's investments in non-U.S. government bonds and asset-backed securities secured by different types of consumer debt (e.g., credit-card receivables, automobile loans, and home equity loans), are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund's foreign currency holdings and investments denominated in foreign currencies. Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund's investments. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's annual total returns from year to year for the periods indicated and by comparing the Fund's average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 9.12% (3Q2009) Lowest Quarter: – 15.24% (4Q2008) Year-to-Date (as of 3/31/16): 1.12%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Core Plus Bond Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.25%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.17%	[2]
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.07%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.64%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.21%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.43%	[4]
1 Year	rr_ExpenseExampleYear01	$ 44
3 Years	rr_ExpenseExampleYear03	197
5 Years	rr_ExpenseExampleYear05	363
10 Years	rr_ExpenseExampleYear10	845
1 Year	rr_ExpenseExampleNoRedemptionYear01	44
3 Years	rr_ExpenseExampleNoRedemptionYear03	197
5 Years	rr_ExpenseExampleNoRedemptionYear05	363
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 845
2006	rr_AnnualReturn2006	5.63%
2007	rr_AnnualReturn2007	(1.44%)
2008	rr_AnnualReturn2008	(19.59%)
2009	rr_AnnualReturn2009	21.70%
2010	rr_AnnualReturn2010	13.27%
2011	rr_AnnualReturn2011	8.76%
2012	rr_AnnualReturn2012	9.98%
2013	rr_AnnualReturn2013	0.49%
2014	rr_AnnualReturn2014	9.54%
2015	rr_AnnualReturn2015	(1.55%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	1.12%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	9.12%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(15.24%)
1 Year	rr_AverageAnnualReturnYear01	(1.55%)
5 Years	rr_AverageAnnualReturnYear05	5.33%
10 Years	rr_AverageAnnualReturnYear10	4.11%
Incept.	rr_AverageAnnualReturnSinceInception	5.54%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 30, 1997
GMO Core Plus Bond Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.25%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.17%	[2]
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.07%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.59%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.21%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.38%	[4]
1 Year	rr_ExpenseExampleYear01	$ 39
3 Years	rr_ExpenseExampleYear03	181
5 Years	rr_ExpenseExampleYear05	335
10 Years	rr_ExpenseExampleYear10	785
1 Year	rr_ExpenseExampleNoRedemptionYear01	39
3 Years	rr_ExpenseExampleNoRedemptionYear03	181
5 Years	rr_ExpenseExampleNoRedemptionYear05	335
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 785
1 Year	rr_AverageAnnualReturnYear01	(1.40%)
5 Years	rr_AverageAnnualReturnYear05	5.38%
10 Years	rr_AverageAnnualReturnYear10	4.15%
Incept.	rr_AverageAnnualReturnSinceInception	4.18%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 26, 2005
GMO Core Plus Bond Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(3.67%)
5 Years	rr_AverageAnnualReturnYear05	3.24%
10 Years	rr_AverageAnnualReturnYear10	1.30%
Incept.	rr_AverageAnnualReturnSinceInception	2.88%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 30, 1997
GMO Core Plus Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.87%)
5 Years	rr_AverageAnnualReturnYear05	3.27%
10 Years	rr_AverageAnnualReturnYear10	1.97%
Incept.	rr_AverageAnnualReturnSinceInception	3.21%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 30, 1997
GMO Core Plus Bond Fund | Barclays U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.55%
5 Years	rr_AverageAnnualReturnYear05	3.25%
10 Years	rr_AverageAnnualReturnYear10	4.52%
Incept.	rr_AverageAnnualReturnSinceInception	5.47%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 30, 1997
GMO Core Plus Bond Fund | Barclays U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.55%
5 Years	rr_AverageAnnualReturnYear05	3.25%
10 Years	rr_AverageAnnualReturnYear10	4.52%
Incept.	rr_AverageAnnualReturnSinceInception	4.40%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 26, 2005

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] The amount includes interest expense incurred by the Fund as a result of entering into reverse repurchase agreements and/or margin on cleared swap contracts, if any. "Other expenses" (before addition of interest expense) and interest expense were approximately 0.16% and 0.01%, respectively.

[3] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.06%, less than 0.01% and 0.01%, respectively.

[4] after expense reimbursement/waiver (Fund and underlying fund expenses)

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GMO Emerging Country Debt Fund

GMO EMERGING COUNTRY DEBT FUND

Investment objective

Total return in excess of that of its benchmark, the J.P. Morgan EMBI Global.

Fees and expenses

The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees - GMO Emerging Country Debt Fund	Class III	Class IV
Purchase premium (as a percentage of amount invested)	0.75%	0.75%
Redemption fee (as a percentage of amount redeemed)	0.75%	0.75%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Emerging Country Debt Fund		Class III	Class IV
Management fee	[1]	0.35%	0.35%
Shareholder service fee	[1]	0.15%	0.10%
Other expenses		0.04%	0.04%
Total annual fund operating expenses		0.54%	0.49%
Expense waiver	[1]	none	none
Total annual fund operating expenses	[2]	0.54%	0.49%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example - GMO Emerging Country Debt Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	208	332	467	862
Class IV	203	316	440	802

If you do not sell your shares

Expense Example, No Redemption - GMO Emerging Country Debt Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	130	247	375	747
Class IV	125	231	347	686

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 20% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 17% of the average value of its portfolio.

Principal investment strategies

The Fund invests primarily in debt of emerging market sovereign or quasi-sovereign issuers that usually is denominated in U.S. dollars, Euros, Japanese yen, Swiss francs or British pounds sterling. "Sovereign" refers to a government and "quasi-sovereign" refers to a governmental agency, political subdivision or other instrumentality or issuer that is majority owned, directly or indirectly, or whose obligations are guaranteed, by a government. Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in debt investments tied economically to emerging countries (see "Name Policies"). The term "emerging countries" means the world's less developed countries. In general, the Fund considers "emerging countries" to be the countries included in the Fund's benchmark, as well as other countries with similar national domestic products or default histories.

The Fund typically gains its investment exposure by purchasing debt investments or by using derivatives, typically credit default swaps. The Fund may invest in debt instruments of all credit qualities, including securities that are in default. (These debt instruments may include below investment grade debt investments, which are sometimes referred to as "junk bonds," although this term is not generally used to refer to emerging country debt securities.) Generally, at least 75% of the Fund's assets are denominated in, or hedged into, U.S. dollars. The Fund's performance is likely to be more volatile than that of its benchmark.

When constructing the portfolio, GMO considers risk at both the portfolio and individual security level and generally takes into account, among other factors, interest rate duration, credit spread duration, and default duration as well as the idiosyncratic risk of each instrument. GMO relies principally on a bottom-up approach using fundamental analytical techniques in selecting investments. GMO also considers its outlook for a country in making investment decisions. The factors GMO considers and investment methods GMO uses can change over time.

In pursuing its investment objective, the Fund typically invests in exchange-traded and over-the-counter (OTC) derivatives, including options, swap contracts (in addition to credit default swaps), currency forwards (including currency forwards on currencies of the developed markets), reverse repurchase agreements and futures. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

GMO normally seeks to maintain an interest rate duration for the Fund that is similar to that of its benchmark (approximately 6.9 years as of 5/31/16). For an additional discussion of duration, see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Bond Funds — Duration."

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. In addition, investments in emerging country sovereign or quasi-sovereign debt involve a heightened risk that the issuer responsible for repayment of the debt may be unable or unwilling to pay interest and repay principal when due, and the Fund may lack recourse against the issuer in the event of default. Investments in quasi-sovereign debt are also subject to the risk that the issuer will default independently of its sovereign. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). In addition, the market prices of emerging country sovereign and quasi-sovereign debt instruments can decline due to uncertainty about their credit quality and the reliability of their payment streams.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund’s benchmark (which is a broad-based index) and a composite index computed by GMO. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 20.29% (3Q2009)
Lowest Quarter: – 23.39% (4Q2008)
Year-to-Date (as of 3/31/16): 4.26%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Emerging Country Debt Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(1.47%)	7.05%	8.30%	14.69%	Apr. 19, 1994
Class III | Return After Taxes on Distributions	(4.49%)	3.74%	4.62%	9.24%	Apr. 19, 1994
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(0.82%)	4.08%	5.00%	9.39%	Apr. 19, 1994
Class III | J.P. Morgan EMBI Global (Fund benchmark) (reflects no deduction for fees, expenses, or taxes)	1.23%	5.11%	6.72%	10.44%	Apr. 19, 1994
Class III | J.P. Morgan EMBI Global + (Composite index)	1.23%	5.11%	6.72%	10.36%	Apr. 19, 1994
Class IV	(1.54%)	7.09%	8.35%	11.25%	Jan. 09, 1998
Class IV | J.P. Morgan EMBI Global (Fund benchmark) (reflects no deduction for fees, expenses, or taxes)	1.23%	5.11%	6.72%	8.58%	Jan. 09, 1998
Class IV | J.P. Morgan EMBI Global + (Composite index)	1.23%	5.11%	6.72%	8.51%	Jan. 09, 1998

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees. During the Fund's most recent fiscal year, the impact of this waiver was less than 0.01%.

[2] after expense waiver

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Emerging Country Debt Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO EMERGING COUNTRY DEBT FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the J.P. Morgan EMBI Global.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 20% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 17% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	20.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests primarily in debt of emerging market sovereign or quasi-sovereign issuers that usually is denominated in U.S. dollars, Euros, Japanese yen, Swiss francs or British pounds sterling. "Sovereign" refers to a government and "quasi-sovereign" refers to a governmental agency, political subdivision or other instrumentality or issuer that is majority owned, directly or indirectly, or whose obligations are guaranteed, by a government. Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in debt investments tied economically to emerging countries (see "Name Policies"). The term "emerging countries" means the world's less developed countries. In general, the Fund considers "emerging countries" to be the countries included in the Fund's benchmark, as well as other countries with similar national domestic products or default histories. The Fund typically gains its investment exposure by purchasing debt investments or by using derivatives, typically credit default swaps. The Fund may invest in debt instruments of all credit qualities, including securities that are in default. (These debt instruments may include below investment grade debt investments, which are sometimes referred to as "junk bonds," although this term is not generally used to refer to emerging country debt securities.) Generally, at least 75% of the Fund's assets are denominated in, or hedged into, U.S. dollars. The Fund's performance is likely to be more volatile than that of its benchmark. When constructing the portfolio, GMO considers risk at both the portfolio and individual security level and generally takes into account, among other factors, interest rate duration, credit spread duration, and default duration as well as the idiosyncratic risk of each instrument. GMO relies principally on a bottom-up approach using fundamental analytical techniques in selecting investments. GMO also considers its outlook for a country in making investment decisions. The factors GMO considers and investment methods GMO uses can change over time. In pursuing its investment objective, the Fund typically invests in exchange-traded and over-the-counter (OTC) derivatives, including options, swap contracts (in addition to credit default swaps), currency forwards (including currency forwards on currencies of the developed markets), reverse repurchase agreements and futures. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds. GMO normally seeks to maintain an interest rate duration for the Fund that is similar to that of its benchmark (approximately 6.9 years as of 5/31/16). For an additional discussion of duration, see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Bond Funds — Duration."
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. In addition, investments in emerging country sovereign or quasi-sovereign debt involve a heightened risk that the issuer responsible for repayment of the debt may be unable or unwilling to pay interest and repay principal when due, and the Fund may lack recourse against the issuer in the event of default. Investments in quasi-sovereign debt are also subject to the risk that the issuer will default independently of its sovereign. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). In addition, the market prices of emerging country sovereign and quasi-sovereign debt instruments can decline due to uncertainty about their credit quality and the reliability of their payment streams. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund’s benchmark (which is a broad-based index) and a composite index computed by GMO. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund’s benchmark (which is a broad-based index) and a composite index computed by GMO.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 20.29% (3Q2009) Lowest Quarter: – 23.39% (4Q2008) Year-to-Date (as of 3/31/16): 4.26%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Emerging Country Debt Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.75%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.75%
Management fee	rr_ManagementFeesOverAssets	0.35%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.04%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.54%
Expense waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.54%	[2]
1 Year	rr_ExpenseExampleYear01	$ 208
3 Years	rr_ExpenseExampleYear03	332
5 Years	rr_ExpenseExampleYear05	467
10 Years	rr_ExpenseExampleYear10	862
1 Year	rr_ExpenseExampleNoRedemptionYear01	130
3 Years	rr_ExpenseExampleNoRedemptionYear03	247
5 Years	rr_ExpenseExampleNoRedemptionYear05	375
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 747
2006	rr_AnnualReturn2006	14.81%
2007	rr_AnnualReturn2007	9.19%
2008	rr_AnnualReturn2008	(33.25%)
2009	rr_AnnualReturn2009	50.17%
2010	rr_AnnualReturn2010	25.64%
2011	rr_AnnualReturn2011	7.50%
2012	rr_AnnualReturn2012	26.73%
2013	rr_AnnualReturn2013	(1.18%)
2014	rr_AnnualReturn2014	5.98%
2015	rr_AnnualReturn2015	0.02%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	4.26%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	20.29%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(23.39%)
1 Year	rr_AverageAnnualReturnYear01	(1.47%)
5 Years	rr_AverageAnnualReturnYear05	7.05%
10 Years	rr_AverageAnnualReturnYear10	8.30%
Incept.	rr_AverageAnnualReturnSinceInception	14.69%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 19, 1994
GMO Emerging Country Debt Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.75%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.75%
Management fee	rr_ManagementFeesOverAssets	0.35%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.04%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.49%
Expense waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.49%	[2]
1 Year	rr_ExpenseExampleYear01	$ 203
3 Years	rr_ExpenseExampleYear03	316
5 Years	rr_ExpenseExampleYear05	440
10 Years	rr_ExpenseExampleYear10	802
1 Year	rr_ExpenseExampleNoRedemptionYear01	125
3 Years	rr_ExpenseExampleNoRedemptionYear03	231
5 Years	rr_ExpenseExampleNoRedemptionYear05	347
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 686
1 Year	rr_AverageAnnualReturnYear01	(1.54%)
5 Years	rr_AverageAnnualReturnYear05	7.09%
10 Years	rr_AverageAnnualReturnYear10	8.35%
Incept.	rr_AverageAnnualReturnSinceInception	11.25%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998
GMO Emerging Country Debt Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(4.49%)
5 Years	rr_AverageAnnualReturnYear05	3.74%
10 Years	rr_AverageAnnualReturnYear10	4.62%
Incept.	rr_AverageAnnualReturnSinceInception	9.24%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 19, 1994
GMO Emerging Country Debt Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.82%)
5 Years	rr_AverageAnnualReturnYear05	4.08%
10 Years	rr_AverageAnnualReturnYear10	5.00%
Incept.	rr_AverageAnnualReturnSinceInception	9.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 19, 1994
GMO Emerging Country Debt Fund | J.P. Morgan EMBI Global (Fund benchmark) (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.23%
5 Years	rr_AverageAnnualReturnYear05	5.11%
10 Years	rr_AverageAnnualReturnYear10	6.72%
Incept.	rr_AverageAnnualReturnSinceInception	10.44%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 19, 1994
GMO Emerging Country Debt Fund | J.P. Morgan EMBI Global (Fund benchmark) (reflects no deduction for fees, expenses, or taxes) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.23%
5 Years	rr_AverageAnnualReturnYear05	5.11%
10 Years	rr_AverageAnnualReturnYear10	6.72%
Incept.	rr_AverageAnnualReturnSinceInception	8.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998
GMO Emerging Country Debt Fund | J.P. Morgan EMBI Global + (Composite index) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.23%
5 Years	rr_AverageAnnualReturnYear05	5.11%
10 Years	rr_AverageAnnualReturnYear10	6.72%
Incept.	rr_AverageAnnualReturnSinceInception	10.36%
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 19, 1994
GMO Emerging Country Debt Fund | J.P. Morgan EMBI Global + (Composite index) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.23%
5 Years	rr_AverageAnnualReturnYear05	5.11%
10 Years	rr_AverageAnnualReturnYear10	6.72%
Incept.	rr_AverageAnnualReturnSinceInception	8.51%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees. During the Fund's most recent fiscal year, the impact of this waiver was less than 0.01%.

[2] after expense waiver

XML

GMO Debt Opportunities Fund

GMO DEBT OPPORTUNITIES FUND

Investment objective

Positive total return.

Fees and expenses

The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees - GMO Debt Opportunities Fund	Class III	Class VI
Purchase premium (as a percentage of amount invested)	0.40%	0.40%
Redemption fee (as a percentage of amount redeemed)	0.40%	0.40%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Debt Opportunities Fund		Class III	Class VI
Management fee	[1]	0.25%	0.25%
Shareholder service fee	[1]	0.15%	0.055%
Other expenses		0.04%	0.04%
Total annual fund operating expenses		0.44%	0.35%
Expense reimbursement/waiver	[1]	(0.04%)	(0.04%)
Total annual fund operating expenses	[2]	0.40%	0.31%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example - GMO Debt Opportunities Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	122	222	331	651
Class VI	113	194	282	540

If you do not sell your shares

Expense Example, No Redemption - GMO Debt Opportunities Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	81	177	282	588
Class VI	72	148	232	477

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 66% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 51% of the average value of its portfolio.

Principal investment strategies

The Fund invests primarily in debt investments (including both direct and indirect investments) and is not restricted in its exposure to any type of debt investment. The Fund may invest in securities of any credit quality and has no limit on how much it may invest in below investment grade securities (commonly referred to as "junk bonds"). The Fund's debt investments may include all types of interest rate, payment, and reset terms, including fixed rate, adjustable rate, zero coupon, contingent, deferred, payment-in-kind, and auction rate features.

The Fund may invest in debt investments issued by a wide range of U.S. and, typically to a lesser extent, non-U.S. private issuers and by federal, state, local, and non-U.S. governments (whether or not guaranteed or insured by those governments). The Fund may invest in asset-backed securities (including, but not limited to, securities backed by pools of residential and commercial mortgages (including sub-prime mortgages), credit-card receivables, home equity loans, automobile loans, educational loans, corporate, sovereign and quasi-sovereign bonds, and bank loans made to corporations, or a combination of bonds and loans (commonly referred to as "collateralized debt obligations" or "collateralized loan obligations")), corporate debt securities, money market instruments, and commercial paper. As of the date of this Prospectus, the Fund has invested a substantial portion of its assets in asset-backed securities, many of which are below investment grade.

In selecting debt investments for the Fund's portfolio, GMO uses analytical techniques to evaluate the relative attractiveness of particular sectors and securities. The factors GMO considers and investment methods GMO uses can change over time.

The Fund does not maintain a specified interest rate duration for its portfolio.

Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in debt investments (see "Name Policies").

From time to time, the Fund may have some direct or indirect exposure to equities. The Fund may invest in securities of companies of any market capitalization.

The Fund also may invest in exchange-traded and over-the-counter (OTC) derivatives, including swap contracts (such as credit default swaps, swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, variance swaps, commodity swaps, inflation swaps, municipal swaps, correlation swaps, and other types of swaps), reverse repurchase agreements, and repurchase agreements. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund may have gross investment exposures in excess of its net assets (i.e., the Fund may be leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

The Fund may, but is not required to, hedge part or all of its net foreign currency exposure into U.S. dollars.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin, or otherwise honor its obligations.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class VI Shares
Years Ending December 31

Highest Quarter: 4.69% (3Q2012)
Lowest Quarter: – 0.08% (3Q2015)
Year-to-Date (as of 3/31/16): – 0.04%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Debt Opportunities Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class VI	[1],[2]	0.86%			5.29%	Oct. 03, 2011
Class VI | Return After Taxes on Distributions	[1],[2]	0.12%			4.06%	Oct. 03, 2011
Class VI | Return After Taxes on Distributions and Sale of Fund Shares	[1],[2]	0.49%			3.71%	Oct. 03, 2011
J.P. Morgan U.S. 3 Month Cash Index (reflects no deduction for fees, expenses, or taxes)	[1],[2]	0.41%			0.50%	Oct. 03, 2011

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees, and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

[1] On December 21, 2015 GMO changed the primary pricing source for certain fixed income asset-backed securities held by the Fund, which resulted in an increase of $0.04 to the December 21, 2015 net asset value of Class VI shares of the Fund.

[2] The Fund is the accounting and performance successor to GMO Debt Opportunities Fund, a former series of GMO Trust offered pursuant to a private placement memorandum (the "Predecessor Fund") that had an investment objective and investment policies and restrictions substantially identical to those of the Fund. Effective February 12, 2014, the Predecessor Fund merged into the Fund (which was formerly known as GMO Short-Duration Collateral Fund), and the surviving entity was renamed "GMO Debt Opportunities Fund." Performance of the Fund through February 12, 2014 is that of the Predecessor Fund and reflects the Predecessor Fund's annual operating expenses (0.01% lower than those of the Fund). For information regarding GMO Short-Duration Collateral Fund's performance history, please see page 236 of this Prospectus.

[1] On December 21, 2015 GMO changed the primary pricing source for certain fixed income asset-backed securities held by the Fund, which resulted in an increase of $0.04 to the December 21, 2015 net asset value of Class VI shares of the Fund.

[2] The Fund is the accounting and performance successor to GMO Debt Opportunities Fund, a former series of GMO Trust offered pursuant to a private placement memorandum (the "Predecessor Fund") that had an investment objective and investment policies and restrictions substantially identical to those of the Fund. Effective February 12, 2014, the Predecessor Fund merged into the Fund (which was formerly known as GMO Short-Duration Collateral Fund), and the surviving entity was renamed "GMO Debt Opportunities Fund." Performance of the Fund through February 12, 2014 is that of the Predecessor Fund and reflects the Predecessor Fund's annual operating expenses (0.01% lower than those of the Fund). For information regarding GMO Short-Duration Collateral Fund's performance history, please see page 236 of this Prospectus.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Debt Opportunities Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO DEBT OPPORTUNITIES FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Positive total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 66% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 51% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	66.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests primarily in debt investments (including both direct and indirect investments) and is not restricted in its exposure to any type of debt investment. The Fund may invest in securities of any credit quality and has no limit on how much it may invest in below investment grade securities (commonly referred to as "junk bonds"). The Fund's debt investments may include all types of interest rate, payment, and reset terms, including fixed rate, adjustable rate, zero coupon, contingent, deferred, payment-in-kind, and auction rate features. The Fund may invest in debt investments issued by a wide range of U.S. and, typically to a lesser extent, non-U.S. private issuers and by federal, state, local, and non-U.S. governments (whether or not guaranteed or insured by those governments). The Fund may invest in asset-backed securities (including, but not limited to, securities backed by pools of residential and commercial mortgages (including sub-prime mortgages), credit-card receivables, home equity loans, automobile loans, educational loans, corporate, sovereign and quasi-sovereign bonds, and bank loans made to corporations, or a combination of bonds and loans (commonly referred to as "collateralized debt obligations" or "collateralized loan obligations")), corporate debt securities, money market instruments, and commercial paper. As of the date of this Prospectus, the Fund has invested a substantial portion of its assets in asset-backed securities, many of which are below investment grade. In selecting debt investments for the Fund's portfolio, GMO uses analytical techniques to evaluate the relative attractiveness of particular sectors and securities. The factors GMO considers and investment methods GMO uses can change over time. The Fund does not maintain a specified interest rate duration for its portfolio. Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in debt investments (see "Name Policies"). From time to time, the Fund may have some direct or indirect exposure to equities. The Fund may invest in securities of companies of any market capitalization. The Fund also may invest in exchange-traded and over-the-counter (OTC) derivatives, including swap contracts (such as credit default swaps, swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, variance swaps, commodity swaps, inflation swaps, municipal swaps, correlation swaps, and other types of swaps), reverse repurchase agreements, and repurchase agreements. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund may have gross investment exposures in excess of its net assets (i.e., the Fund may be leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds. The Fund may, but is not required to, hedge part or all of its net foreign currency exposure into U.S. dollars.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Illiquidity Risk – Low trading volume, lack of a market maker, large position size or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Leveraging Risk – The use of reverse repurchase agreements and other derivatives creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin, or otherwise honor its obligations. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class VI Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 4.69% (3Q2012) Lowest Quarter: – 0.08% (3Q2015) Year-to-Date (as of 3/31/16): – 0.04%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Debt Opportunities Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.40%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.40%
Management fee	rr_ManagementFeesOverAssets	0.25%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.04%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.44%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.40%	[2]
1 Year	rr_ExpenseExampleYear01	$ 122
3 Years	rr_ExpenseExampleYear03	222
5 Years	rr_ExpenseExampleYear05	331
10 Years	rr_ExpenseExampleYear10	651
1 Year	rr_ExpenseExampleNoRedemptionYear01	81
3 Years	rr_ExpenseExampleNoRedemptionYear03	177
5 Years	rr_ExpenseExampleNoRedemptionYear05	282
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 588
GMO Debt Opportunities Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.40%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.40%
Management fee	rr_ManagementFeesOverAssets	0.25%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.04%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.35%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.31%	[2]
1 Year	rr_ExpenseExampleYear01	$ 113
3 Years	rr_ExpenseExampleYear03	194
5 Years	rr_ExpenseExampleYear05	282
10 Years	rr_ExpenseExampleYear10	540
1 Year	rr_ExpenseExampleNoRedemptionYear01	72
3 Years	rr_ExpenseExampleNoRedemptionYear03	148
5 Years	rr_ExpenseExampleNoRedemptionYear05	232
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 477
2012	rr_AnnualReturn2012	11.90%	[3],[4]
2013	rr_AnnualReturn2013	5.76%	[3],[4]
2014	rr_AnnualReturn2014	4.45%	[3],[4]
2015	rr_AnnualReturn2015	1.67%	[3],[4]
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(0.04%)	[3],[4]
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	4.69%	[3],[4]
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(0.08%)	[3],[4]
1 Year	rr_AverageAnnualReturnYear01	0.86%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05		[3],[4]
10 Years	rr_AverageAnnualReturnYear10		[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception	5.29%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 03, 2011	[3],[4]
GMO Debt Opportunities Fund | Return After Taxes on Distributions | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.12%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05		[3],[4]
10 Years	rr_AverageAnnualReturnYear10		[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception	4.06%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 03, 2011	[3],[4]
GMO Debt Opportunities Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.49%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05		[3],[4]
10 Years	rr_AverageAnnualReturnYear10		[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception	3.71%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 03, 2011	[3],[4]
GMO Debt Opportunities Fund | J.P. Morgan U.S. 3 Month Cash Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.41%	[3],[4]
5 Years	rr_AverageAnnualReturnYear05		[3],[4]
10 Years	rr_AverageAnnualReturnYear10		[3],[4]
Incept.	rr_AverageAnnualReturnSinceInception	0.50%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 03, 2011	[3],[4]

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees, and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

[3] On December 21, 2015 GMO changed the primary pricing source for certain fixed income asset-backed securities held by the Fund, which resulted in an increase of $0.04 to the December 21, 2015 net asset value of Class VI shares of the Fund.

[4] The Fund is the accounting and performance successor to GMO Debt Opportunities Fund, a former series of GMO Trust offered pursuant to a private placement memorandum (the "Predecessor Fund") that had an investment objective and investment policies and restrictions substantially identical to those of the Fund. Effective February 12, 2014, the Predecessor Fund merged into the Fund (which was formerly known as GMO Short-Duration Collateral Fund), and the surviving entity was renamed "GMO Debt Opportunities Fund." Performance of the Fund through February 12, 2014 is that of the Predecessor Fund and reflects the Predecessor Fund's annual operating expenses (0.01% lower than those of the Fund). For information regarding GMO Short-Duration Collateral Fund's performance history, please see page 236 of this Prospectus.

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GMO Alpha Only Fund

GMO ALPHA ONLY FUND

Investment objective

Total return greater than that of its benchmark, the Citigroup 3-Month Treasury Bill Index.

Fees and expenses

The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Alpha Only Fund		Class III	Class IV
Management fee	[1]	0.50%	0.50%
Shareholder service fee	[1]	0.15%	0.10%
Other expenses		0.07%	0.06%
Total annual fund operating expenses		0.72%	0.66%
Expense reimbursement/waiver	[1]	(0.06%)	(0.06%)
Total annual fund operating expenses	[2]	0.66%	0.60%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - GMO Alpha Only Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	67	224	395	889
Class IV	61	205	362	817

Expense Example, No Redemption - GMO Alpha Only Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	67	224	395	889
Class IV	61	205	362	817

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 85% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 31% of the average value of its portfolio.

Principal investment strategies

GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other funds or accounts managed by GMO. Accordingly, the Fund is not a standalone investment.

The Fund's investment program involves having both long and short investment exposures. GMO seeks to construct a portfolio in which the Fund has long investment exposure to asset classes and sub-asset classes that GMO expects will outperform relative to the asset classes and sub-asset classes to which the Fund has short investment exposure.

To gain long investment exposure, the Fund invests directly in securities and may invest in other GMO Funds (collectively, the "underlying GMO Funds"). To gain short investment exposure, the Fund typically invests in over-the-counter (OTC) and exchange-traded derivatives (including futures, swaps and currency forwards) and sells securities short, including short sales of securities the Fund does not own. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund's long and short positions. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund's holdings in response to changes in GMO's investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund's investments. If the Fund's long and short positions are effective, the Fund's performance should have a low correlation to the performance of U.S. and non-U.S. equity markets. The factors GMO considers and investment methods GMO uses can change over time.

The Fund may invest in securities of any credit quality (including below investment grade securities (commonly referred to as "junk bonds")). The Fund may invest in securities of companies of any market capitalization.

In seeking to achieve the Fund's investment objective, GMO may invest a significant portion of the Fund's net assets in cash and cash equivalents. GMO would not consider such investments to be "temporary defensive positions."

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. An investment in the Fund is subject to different risks, and greater overall risk, than an investment in the components of the Fund’s benchmark. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). The Fund and some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund or those underlying funds may affect the Fund’s or an underlying fund’s performance more than if the Fund or the underlying fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.”

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund or an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund or an underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. In addition, the value of the Fund’s shares will be adversely affected if the equities that are the subject of the Fund’s short positions appreciate in value.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives creates leverage. The Fund and some underlying funds are not limited in their use of derivatives or in the total notional value of their derivative positions. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities (commonly referred to as “junk bonds”) have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected or that the Fund will invest in underlying funds with higher fees or expenses.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 5.32% (4Q2008)
Lowest Quarter: – 4.81% (2Q2009)
Year-to-Date (as of 3/31/16): 2.49%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Alpha Only Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(1.27%)	(0.44%)	0.74%	3.09%	Jul. 29, 1994
Class III | Return After Taxes on Distributions	(2.36%)	(0.76%)	(1.56%)	1.08%	Jul. 29, 1994
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(0.17%)	(0.30%)	0.41%	1.95%	Jul. 29, 1994
Class III | Citigroup 3-Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes)	0.03%	0.05%	1.17%	2.64%	Jul. 29, 1994
Class IV	(1.19%)	(0.39%)		0.68%	Mar. 02, 2006
Class IV | Citigroup 3-Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes)	0.03%	0.05%		1.12%	Mar. 02, 2006

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Alpha Only Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO ALPHA ONLY FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return greater than that of its benchmark, the Citigroup 3-Month Treasury Bill Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 85% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 31% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	85.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other funds or accounts managed by GMO. Accordingly, the Fund is not a standalone investment. The Fund's investment program involves having both long and short investment exposures. GMO seeks to construct a portfolio in which the Fund has long investment exposure to asset classes and sub-asset classes that GMO expects will outperform relative to the asset classes and sub-asset classes to which the Fund has short investment exposure. To gain long investment exposure, the Fund invests directly in securities and may invest in other GMO Funds (collectively, the "underlying GMO Funds"). To gain short investment exposure, the Fund typically invests in over-the-counter (OTC) and exchange-traded derivatives (including futures, swaps and currency forwards) and sells securities short, including short sales of securities the Fund does not own. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund's long and short positions. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund's holdings in response to changes in GMO's investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund's investments. If the Fund's long and short positions are effective, the Fund's performance should have a low correlation to the performance of U.S. and non-U.S. equity markets. The factors GMO considers and investment methods GMO uses can change over time. The Fund may invest in securities of any credit quality (including below investment grade securities (commonly referred to as "junk bonds")). The Fund may invest in securities of companies of any market capitalization. In seeking to achieve the Fund's investment objective, GMO may invest a significant portion of the Fund's net assets in cash and cash equivalents. GMO would not consider such investments to be "temporary defensive positions." The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. An investment in the Fund is subject to different risks, and greater overall risk, than an investment in the components of the Fund’s benchmark. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). The Fund and some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund or those underlying funds may affect the Fund’s or an underlying fund’s performance more than if the Fund or the underlying fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.” Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund or an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund or an underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. In addition, the value of the Fund’s shares will be adversely affected if the equities that are the subject of the Fund’s short positions appreciate in value. Leveraging Risk – The use of reverse repurchase agreements and other derivatives creates leverage. The Fund and some underlying funds are not limited in their use of derivatives or in the total notional value of their derivative positions. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Illiquidity Risk – Low trading volume, lack of a market maker, large position size or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities (commonly referred to as “junk bonds”) have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected or that the Fund will invest in underlying funds with higher fees or expenses.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund and some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund or those underlying funds may affect the Fund’s or an underlying fund’s performance more than if the Fund or the underlying fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 5.32% (4Q2008) Lowest Quarter: – 4.81% (2Q2009) Year-to-Date (as of 3/31/16): 2.49%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Alpha Only Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.50%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.07%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.72%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.06%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.66%	[2]
1 Year	rr_ExpenseExampleYear01	$ 67
3 Years	rr_ExpenseExampleYear03	224
5 Years	rr_ExpenseExampleYear05	395
10 Years	rr_ExpenseExampleYear10	889
1 Year	rr_ExpenseExampleNoRedemptionYear01	67
3 Years	rr_ExpenseExampleNoRedemptionYear03	224
5 Years	rr_ExpenseExampleNoRedemptionYear05	395
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 889
2006	rr_AnnualReturn2006	3.34%
2007	rr_AnnualReturn2007	7.60%
2008	rr_AnnualReturn2008	12.08%
2009	rr_AnnualReturn2009	(7.93%)
2010	rr_AnnualReturn2010	(4.02%)
2011	rr_AnnualReturn2011	4.73%
2012	rr_AnnualReturn2012	(1.21%)
2013	rr_AnnualReturn2013	(1.43%)
2014	rr_AnnualReturn2014	(2.87%)
2015	rr_AnnualReturn2015	(1.27%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	2.49%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2008
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	5.32%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2009
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(4.81%)
1 Year	rr_AverageAnnualReturnYear01	(1.27%)
5 Years	rr_AverageAnnualReturnYear05	(0.44%)
10 Years	rr_AverageAnnualReturnYear10	0.74%
Incept.	rr_AverageAnnualReturnSinceInception	3.09%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 1994
GMO Alpha Only Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.50%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.06%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.66%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.06%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.60%	[2]
1 Year	rr_ExpenseExampleYear01	$ 61
3 Years	rr_ExpenseExampleYear03	205
5 Years	rr_ExpenseExampleYear05	362
10 Years	rr_ExpenseExampleYear10	817
1 Year	rr_ExpenseExampleNoRedemptionYear01	61
3 Years	rr_ExpenseExampleNoRedemptionYear03	205
5 Years	rr_ExpenseExampleNoRedemptionYear05	362
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 817
1 Year	rr_AverageAnnualReturnYear01	(1.19%)
5 Years	rr_AverageAnnualReturnYear05	(0.39%)
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.68%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 02, 2006
GMO Alpha Only Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.36%)
5 Years	rr_AverageAnnualReturnYear05	(0.76%)
10 Years	rr_AverageAnnualReturnYear10	(1.56%)
Incept.	rr_AverageAnnualReturnSinceInception	1.08%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 1994
GMO Alpha Only Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.17%)
5 Years	rr_AverageAnnualReturnYear05	(0.30%)
10 Years	rr_AverageAnnualReturnYear10	0.41%
Incept.	rr_AverageAnnualReturnSinceInception	1.95%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 1994
GMO Alpha Only Fund | Citigroup 3-Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.03%
5 Years	rr_AverageAnnualReturnYear05	0.05%
10 Years	rr_AverageAnnualReturnYear10	1.17%
Incept.	rr_AverageAnnualReturnSinceInception	2.64%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 1994
GMO Alpha Only Fund | Citigroup 3-Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.03%
5 Years	rr_AverageAnnualReturnYear05	0.05%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 02, 2006

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

XML

GMO Asset Allocation Bond Fund

GMO ASSET ALLOCATION BOND FUND

Investment objective

Total return in excess of that of its benchmark, the Citigroup 3-Month Treasury Bill Index.

Fees and expenses

The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Asset Allocation Bond Fund		Class III	Class VI
Management fee	[1]	0.25%	0.25%
Shareholder service fee	[1]	0.15%	0.055%
Other expenses	[2]	0.05%	0.05%
Total annual fund operating expenses		0.45%	0.36%
Expense reimbursement/waiver	[1]	(0.03%)	(0.03%)
Total annual fund operating expenses	[3]	0.42%	0.33%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - GMO Asset Allocation Bond Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	43	144	254	575
Class VI	34	115	204	464

Expense Example, No Redemption - GMO Asset Allocation Bond Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	43	144	254	575
Class VI	34	115	204	464

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 177% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 123% of the average value of its portfolio.

Principal investment strategies

GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other funds or accounts managed by GMO. Accordingly, the Fund is not a standalone investment.

The Fund invests in a portfolio of fixed income instruments of varying maturities, which may be represented by bonds, forwards or derivatives such as options, futures contracts, or swap agreements. GMO uses a variety of fundamental and quantitative processes to manage the Fund. GMO evaluates the relative attractiveness of particular markets and instruments using various fixed income risk premium measures, which typically include exposure to term structure, foreign exchange, volatility, credit, liquidity and other risks.

Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in bonds (see "Name Policies"). The term "bond" includes (i) obligations of an issuer to make payments on future dates of principal, interest (whether fixed or variable) or both and (ii) synthetic debt instruments created by GMO by using derivatives (e.g., a futures contract, swap contract, currency forward, or option). The Fund is permitted to invest in bonds of any kind (e.g., bonds of any maturity, duration, or credit quality).

The Fund may invest in any sector of the bond market and is not required to maintain a minimum or maximum allocation of investments in any one sector. The sectors and types of bonds in which the Fund may invest include, but are not limited to:

• investment grade bonds denominated in various currencies, including bonds issued by the U.S. and non-U.S. governments and their respective agencies or instrumentalities (whether or not guaranteed or insured by those governments), corporations and municipalities (taxable and tax-exempt);

• below investment grade bonds (commonly referred to as "junk bonds");

• inflation-indexed bonds issued by the U.S. government (including Inflation-Protected Securities issued by the U.S. Treasury (TIPS)) and non-U.S. governments and their respective agencies or instrumentalities (whether or not guaranteed or insured by those governments) and inflation-indexed bonds issued by corporations;

• bonds issued in emerging countries (including sovereign and quasi-sovereign debt and below investment grade bonds);

• asset-backed securities, including mortgage related and mortgage-backed securities;

• pooled investment vehicles, including both vehicles managed by GMO and vehicles unaffiliated with GMO; and

• commodities.

From time to time, the Fund may have some direct or indirect exposure to equities. The Fund may invest in securities of companies of any market capitalization.

The Fund also may invest in exchange-traded and over-the-counter (OTC) derivatives, including futures contracts, currency options, currency forwards, reverse repurchase agreements, swap contracts (such as credit default swaps, swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, variance swaps, commodity swaps, inflation swaps, municipal swaps, correlation swaps, and other types of swaps), interest rate options, and other types of derivatives. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

The Fund may gain exposure to the investments described above by investing in shares of other GMO Funds, including Debt Opportunities Fund (to provide exposure to credit (particularly, asset-backed) markets) and Emerging Country Debt Fund (to provide exposure to emerging country debt securities). The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

The Fund may invest up to 100% of its assets in below investment grade bonds.

GMO does not seek to maintain a specified interest rate duration for the Fund, and the Fund's interest rate duration will change depending on the Fund's investments and GMO's assessment of different sectors of the bond market. The Fund's interest rate duration may be positive or negative. The Fund's performance may differ significantly from that of its benchmark.

In seeking to achieve the Fund's investment objective, GMO may invest a significant portion of the Fund's net assets in cash and cash equivalents. GMO would not consider such investments to be "temporary defensive positions."

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. An investment in the Fund is subject to different risks, and greater overall risk, than an investment in the components of the Fund’s benchmark. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 3.53% (2Q2014)
Lowest Quarter: – 2.83% (4Q2013)
Year-to-Date (as of 3/31/16): 1.09%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Asset Allocation Bond Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(5.93%)	1.38%		2.53%	Mar. 27, 2009
Class III | Return After Taxes on Distributions	(8.67%)	(0.06%)		0.86%	Mar. 27, 2009
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(3.31%)	0.51%		1.34%	Mar. 27, 2009
Class III | Citigroup 3-Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes)	0.03%	0.05%		0.08%	Mar. 27, 2009
Class VI	(5.85%)	1.47%		2.71%	Mar. 18, 2009
Class VI | Citigroup 3-Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes)	0.03%	0.05%		0.08%	Mar. 18, 2009

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] The amount includes interest expense incurred by the Fund as a result of entering into reverse repurchase agreements and/or margin on cleared swap contracts, if any. "Other expenses" (before addition of interest expense) and interest expense were approximately 0.03% and 0.02%, respectively.

[3] after expense reimbursement/waiver

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Asset Allocation Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO ASSET ALLOCATION BOND FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the Citigroup 3-Month Treasury Bill Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 177% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 123% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	177.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other funds or accounts managed by GMO. Accordingly, the Fund is not a standalone investment. The Fund invests in a portfolio of fixed income instruments of varying maturities, which may be represented by bonds, forwards or derivatives such as options, futures contracts, or swap agreements. GMO uses a variety of fundamental and quantitative processes to manage the Fund. GMO evaluates the relative attractiveness of particular markets and instruments using various fixed income risk premium measures, which typically include exposure to term structure, foreign exchange, volatility, credit, liquidity and other risks. Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in bonds (see "Name Policies"). The term "bond" includes (i) obligations of an issuer to make payments on future dates of principal, interest (whether fixed or variable) or both and (ii) synthetic debt instruments created by GMO by using derivatives (e.g., a futures contract, swap contract, currency forward, or option). The Fund is permitted to invest in bonds of any kind (e.g., bonds of any maturity, duration, or credit quality). The Fund may invest in any sector of the bond market and is not required to maintain a minimum or maximum allocation of investments in any one sector. The sectors and types of bonds in which the Fund may invest include, but are not limited to: investment grade bonds denominated in various currencies, including bonds issued by the U.S. and non-U.S. governments and their respective agencies or instrumentalities (whether or not guaranteed or insured by those governments), corporations and municipalities (taxable and tax-exempt); below investment grade bonds (commonly referred to as "junk bonds"); inflation-indexed bonds issued by the U.S. government (including Inflation-Protected Securities issued by the U.S. Treasury (TIPS)) and non-U.S. governments and their respective agencies or instrumentalities (whether or not guaranteed or insured by those governments) and inflation-indexed bonds issued by corporations; bonds issued in emerging countries (including sovereign and quasi-sovereign debt and below investment grade bonds); asset-backed securities, including mortgage related and mortgage-backed securities; pooled investment vehicles, including both vehicles managed by GMO and vehicles unaffiliated with GMO; and commodities. From time to time, the Fund may have some direct or indirect exposure to equities. The Fund may invest in securities of companies of any market capitalization. The Fund also may invest in exchange-traded and over-the-counter (OTC) derivatives, including futures contracts, currency options, currency forwards, reverse repurchase agreements, swap contracts (such as credit default swaps, swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, variance swaps, commodity swaps, inflation swaps, municipal swaps, correlation swaps, and other types of swaps), interest rate options, and other types of derivatives. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices. The Fund may gain exposure to the investments described above by investing in shares of other GMO Funds, including Debt Opportunities Fund (to provide exposure to credit (particularly, asset-backed) markets) and Emerging Country Debt Fund (to provide exposure to emerging country debt securities). The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds. The Fund may invest up to 100% of its assets in below investment grade bonds. GMO does not seek to maintain a specified interest rate duration for the Fund, and the Fund's interest rate duration will change depending on the Fund's investments and GMO's assessment of different sectors of the bond market. The Fund's interest rate duration may be positive or negative. The Fund's performance may differ significantly from that of its benchmark. In seeking to achieve the Fund's investment objective, GMO may invest a significant portion of the Fund's net assets in cash and cash equivalents. GMO would not consider such investments to be "temporary defensive positions."
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. An investment in the Fund is subject to different risks, and greater overall risk, than an investment in the components of the Fund’s benchmark. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 3.53% (2Q2014) Lowest Quarter: – 2.83% (4Q2013) Year-to-Date (as of 3/31/16): 1.09%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Asset Allocation Bond Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.25%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.05%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.45%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.03%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.42%	[3]
1 Year	rr_ExpenseExampleYear01	$ 43
3 Years	rr_ExpenseExampleYear03	144
5 Years	rr_ExpenseExampleYear05	254
10 Years	rr_ExpenseExampleYear10	575
1 Year	rr_ExpenseExampleNoRedemptionYear01	43
3 Years	rr_ExpenseExampleNoRedemptionYear03	144
5 Years	rr_ExpenseExampleNoRedemptionYear05	254
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 575
2010	rr_AnnualReturn2010	4.02%
2011	rr_AnnualReturn2011	5.63%
2012	rr_AnnualReturn2012	0.55%
2013	rr_AnnualReturn2013	(2.15%)
2014	rr_AnnualReturn2014	9.52%
2015	rr_AnnualReturn2015	(5.93%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	1.09%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2014
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	3.53%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2013
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(2.83%)
1 Year	rr_AverageAnnualReturnYear01	(5.93%)
5 Years	rr_AverageAnnualReturnYear05	1.38%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	2.53%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 27, 2009
GMO Asset Allocation Bond Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.25%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.05%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.36%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.03%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.33%	[3]
1 Year	rr_ExpenseExampleYear01	$ 34
3 Years	rr_ExpenseExampleYear03	115
5 Years	rr_ExpenseExampleYear05	204
10 Years	rr_ExpenseExampleYear10	464
1 Year	rr_ExpenseExampleNoRedemptionYear01	34
3 Years	rr_ExpenseExampleNoRedemptionYear03	115
5 Years	rr_ExpenseExampleNoRedemptionYear05	204
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 464
1 Year	rr_AverageAnnualReturnYear01	(5.85%)
5 Years	rr_AverageAnnualReturnYear05	1.47%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	2.71%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 18, 2009
GMO Asset Allocation Bond Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(8.67%)
5 Years	rr_AverageAnnualReturnYear05	(0.06%)
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.86%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 27, 2009
GMO Asset Allocation Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(3.31%)
5 Years	rr_AverageAnnualReturnYear05	0.51%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.34%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 27, 2009
GMO Asset Allocation Bond Fund | Citigroup 3-Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.03%
5 Years	rr_AverageAnnualReturnYear05	0.05%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.08%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 27, 2009
GMO Asset Allocation Bond Fund | Citigroup 3-Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes) | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.03%
5 Years	rr_AverageAnnualReturnYear05	0.05%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.08%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 18, 2009

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] The amount includes interest expense incurred by the Fund as a result of entering into reverse repurchase agreements and/or margin on cleared swap contracts, if any. "Other expenses" (before addition of interest expense) and interest expense were approximately 0.03% and 0.02%, respectively.

[3] after expense reimbursement/waiver

XML

GMO Benchmark-Free Fund

GMO BENCHMARK-FREE FUND

Investment objective

Positive total return.

Fees and expenses

The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees	GMO Benchmark-Free Fund Class III
Purchase premium (as a percentage of amount invested)	0.25%
Redemption fee (as a percentage of amount redeemed)	0.25%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Benchmark-Free Fund Class III
Management fee	none
Shareholder service fee	none
Other expenses	0.02%
Acquired fund fees and expenses (underlying fund expenses)	0.53%	[1]
Total annual fund operating expenses	0.55%
Expense reimbursement	(0.02%)	[2]
Total annual fund operating expenses	0.53%	[3]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Benchmark-Free Fund | Class III | USD ($)	105	234	374	783

If you do not sell your shares

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Benchmark-Free Fund | Class III | USD ($)	79	205	343	744

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 101% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 67% of the average value of its portfolio.

Principal investment strategies

The Fund is a fund of funds and invests primarily in shares of other series of GMO Trust (each, a "GMO Fund"). The Fund may invest in any GMO Fund (collectively, the "underlying GMO Funds"), whether now existing or created in the future. These underlying GMO Funds may include, among others, the Equity Funds, the Fixed Income Funds, the Implementation Funds, and SGM Major Markets Fund (see "Additional Information About the Fund's Investment Strategies, Risks and Expenses — Asset Allocation Funds"). The Fund also may invest directly in securities (particularly asset-backed securities, and including other underlying funds).

GMO implements the Fund's strategy by allocating its assets among asset classes represented by the underlying GMO Funds (e.g., non-U.S. equity, U.S. equity, emerging country equity, emerging country debt, non-U.S. fixed income, U.S. fixed income and commodities). The Fund is not restricted in its exposure to any particular asset class, and at times may be substantially invested in underlying GMO Funds that primarily invest in a single asset class (e.g., Fixed Income Funds). In addition, the Fund is not restricted in its exposure to any particular market, capitalization range, credit quality (i.e., the Fund may invest in below investment grade securities (commonly referred to as "junk bonds")), or maturity. At times, the Fund may have substantial exposure to a particular country or type of country (including non-U.S. countries). GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark.

GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to select the underlying GMO Funds in which the Fund invests and to decide how much to invest in each. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund's holdings of the underlying GMO Funds in response to changes in GMO's investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund's investments. GMO's ability to shift investments among the underlying GMO Funds is not subject to any limits. The Fund may invest substantially all of its assets in a few underlying GMO Funds that primarily invest in the same asset class and may, at times, also invest a substantial portion of its assets in a single underlying GMO Fund. The Fund may have indirect exposure to derivatives and short sales through its investment in other underlying GMO Funds. The Fund also reserves the right to invest directly in asset classes, or to adjust its exposure to asset classes, through direct investments. The factors GMO considers and investment methods GMO uses can change over time.

The Fund may gain exposure to commodities and some other asset classes by investing through a wholly-owned subsidiary advised by GMO, which does not receive management or other fees for its services. The subsidiary invests primarily in commodity-related derivatives and fixed income securities but also may gain exposure to any other investment in which the Fund is permitted to invest directly. References in this Prospectus to the Fund may refer to actions undertaken by the subsidiary as well as the Fund. The Fund does not invest directly in commodities and commodity-related derivatives, but may do so indirectly through its subsidiary company (or otherwise).

In seeking to achieve the Fund's investment objective, GMO may invest a significant portion of the Fund's net assets in cash and cash equivalents. GMO would not consider such investments to be "temporary defensive positions."

The Fund also may invest in in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in its wholly-owned subsidiary and in the underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.”

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Futures Contracts Risk – The risk of loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile and the use of futures contracts may increase the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time and the Fund might be unable to effect closing transactions to terminate its exposure to the contract. If the Fund uses futures contracts for hedging purposes, it runs the risk of imperfect correlation between changes in the prices of the contracts and changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are the subject of the hedge. In addition, the Fund may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts may be less liquid and more volatile than U.S. contracts.

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee.

• Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner.

• Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin, or otherwise honor its obligations.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Year Index and the Consumer Price Index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 5.96% (1Q2012)
Lowest Quarter: – 6.74% (3Q2015)
Year-to-Date (as of 3/31/16): 1.13%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Benchmark-Free Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(3.67%)			4.94%	Jun. 15, 2011
Class III | Return After Taxes on Distributions	(5.62%)			2.84%	Jun. 15, 2011
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(1.40%)			3.58%	Jun. 15, 2011
Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes)	(0.52%)			0.60%	Jun. 15, 2011
Consumer Price Index (reflects no deduction for fees, expenses, or taxes)	0.72%			1.27%	Jun. 15, 2011

[1] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees (“transaction fees”) charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.42%, less than 0.01%, and 0.11%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC (“GMO”) has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees, and the Fund’s direct non-emerging market custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Benchmark-Free Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO BENCHMARK-FREE FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Positive total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 101% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 67% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	101.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund is a fund of funds and invests primarily in shares of other series of GMO Trust (each, a "GMO Fund"). The Fund may invest in any GMO Fund (collectively, the "underlying GMO Funds"), whether now existing or created in the future. These underlying GMO Funds may include, among others, the Equity Funds, the Fixed Income Funds, the Implementation Funds, and SGM Major Markets Fund (see "Additional Information About the Fund's Investment Strategies, Risks and Expenses — Asset Allocation Funds"). The Fund also may invest directly in securities (particularly asset-backed securities, and including other underlying funds). GMO implements the Fund's strategy by allocating its assets among asset classes represented by the underlying GMO Funds (e.g., non-U.S. equity, U.S. equity, emerging country equity, emerging country debt, non-U.S. fixed income, U.S. fixed income and commodities). The Fund is not restricted in its exposure to any particular asset class, and at times may be substantially invested in underlying GMO Funds that primarily invest in a single asset class (e.g., Fixed Income Funds). In addition, the Fund is not restricted in its exposure to any particular market, capitalization range, credit quality (i.e., the Fund may invest in below investment grade securities (commonly referred to as "junk bonds")), or maturity. At times, the Fund may have substantial exposure to a particular country or type of country (including non-U.S. countries). GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to select the underlying GMO Funds in which the Fund invests and to decide how much to invest in each. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund's holdings of the underlying GMO Funds in response to changes in GMO's investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund's investments. GMO's ability to shift investments among the underlying GMO Funds is not subject to any limits. The Fund may invest substantially all of its assets in a few underlying GMO Funds that primarily invest in the same asset class and may, at times, also invest a substantial portion of its assets in a single underlying GMO Fund. The Fund may have indirect exposure to derivatives and short sales through its investment in other underlying GMO Funds. The Fund also reserves the right to invest directly in asset classes, or to adjust its exposure to asset classes, through direct investments. The factors GMO considers and investment methods GMO uses can change over time. The Fund may gain exposure to commodities and some other asset classes by investing through a wholly-owned subsidiary advised by GMO, which does not receive management or other fees for its services. The subsidiary invests primarily in commodity-related derivatives and fixed income securities but also may gain exposure to any other investment in which the Fund is permitted to invest directly. References in this Prospectus to the Fund may refer to actions undertaken by the subsidiary as well as the Fund. The Fund does not invest directly in commodities and commodity-related derivatives, but may do so indirectly through its subsidiary company (or otherwise). In seeking to achieve the Fund's investment objective, GMO may invest a significant portion of the Fund's net assets in cash and cash equivalents. GMO would not consider such investments to be "temporary defensive positions." The Fund also may invest in in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in its wholly-owned subsidiary and in the underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.” Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Futures Contracts Risk – The risk of loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile and the use of futures contracts may increase the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time and the Fund might be unable to effect closing transactions to terminate its exposure to the contract. If the Fund uses futures contracts for hedging purposes, it runs the risk of imperfect correlation between changes in the prices of the contracts and changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are the subject of the hedge. In addition, the Fund may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts may be less liquid and more volatile than U.S. contracts. Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee. Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner. Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated. Illiquidity Risk – Low trading volume, lack of a market maker, large position size or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin, or otherwise honor its obligations. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Year Index and the Consumer Price Index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Year Index and the Consumer Price Index.
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 5.96% (1Q2012) Lowest Quarter: – 6.74% (3Q2015) Year-to-Date (as of 3/31/16): 1.13%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Benchmark-Free Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.25%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.25%
Management fee	rr_ManagementFeesOverAssets	none
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.02%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.53%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.55%
Expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.53%	[3]
1 Year	rr_ExpenseExampleYear01	$ 105
3 Years	rr_ExpenseExampleYear03	234
5 Years	rr_ExpenseExampleYear05	374
10 Years	rr_ExpenseExampleYear10	783
1 Year	rr_ExpenseExampleNoRedemptionYear01	79
3 Years	rr_ExpenseExampleNoRedemptionYear03	205
5 Years	rr_ExpenseExampleNoRedemptionYear05	343
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 744
2012	rr_AnnualReturn2012	10.95%
2013	rr_AnnualReturn2013	12.70%
2014	rr_AnnualReturn2014	1.94%
2015	rr_AnnualReturn2015	(3.19%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	1.13%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	5.96%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(6.74%)
1 Year	rr_AverageAnnualReturnYear01	(3.67%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	4.94%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 15, 2011
GMO Benchmark-Free Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(5.62%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	2.84%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 15, 2011
GMO Benchmark-Free Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(1.40%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	3.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 15, 2011
GMO Benchmark-Free Fund | Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.52%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.60%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 15, 2011
GMO Benchmark-Free Fund | Consumer Price Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.72%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.27%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 15, 2011

[1] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees (“transaction fees”) charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.42%, less than 0.01%, and 0.11%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC (“GMO”) has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees, and the Fund’s direct non-emerging market custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

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GMO Implementation Fund

GMO IMPLEMENTATION FUND

Investment objective

Positive total return, not “relative return.”

Fees and expenses

The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees	GMO Implementation Fund GMO Implementation Fund
Purchase premium (as a percentage of amount invested)	0.20%
Redemption fee (as a percentage of amount redeemed)	0.20%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Implementation Fund GMO Implementation Fund
Management fee	none
Other expenses	0.12%	[1]
Total annual fund operating expenses	0.12%
Expense reimbursement	(0.05%)	[2]
Total annual fund operating expenses	0.07%	[3]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Implementation Fund | GMO Implementation Fund | USD ($)	48	77	108	201

If you do not sell your shares

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Implementation Fund | GMO Implementation Fund | USD ($)	27	54	83	168

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (including the accounts of the Fund’s wholly-owned subsidiary, GMO Implementation SPC Ltd., and excluding short-term investments) was 127% of the average value of its portfolio.

Principal investment strategies

GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other funds or accounts managed by GMO. Accordingly, the Fund is not a standalone investment.

GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund's strategic direction. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. The factors GMO considers and investment methods GMO uses can change over time.

GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. Depending on GMO's outlook, the Fund may have exposure to any asset class (e.g., non-U.S. equity, U.S. equity, emerging country equity, emerging country debt, non-U.S. fixed income, U.S. fixed income, real estate, and commodities) and at times may be substantially invested in a single asset class. The Fund may invest in securities of companies of any market capitalization. In addition, the Fund is not limited in how much it may invest in any market, and it may invest all of its assets in the securities of a limited number of companies in a single country and/or capitalization range. The Fund may invest a significant portion of its assets in the securities of issuers in industries that are subject to the same or similar risk factors. To the extent the Fund invests in fixed income securities, it may have significant exposure to fixed income instruments of any credit quality, including those that are below investment grade (commonly referred to as "junk bonds") and having any maturity or duration. The Fund also may have exposure to short sales. GMO's ability to shift investments among asset classes is not subject to any limits.

The Fund may engage in transactions in which it purchases securities at prices below the value of the consideration GMO expects to be paid for them upon consummation of a proposed merger, exchange offer, tender offer, or other similar transaction ("merger arbitrage transactions"). The purchase price may substantially exceed the market price of the securities before the announcement of the transaction.

In conjunction with merger arbitrage transactions, the Fund may invest in derivatives or sell securities short in an effort to protect against market fluctuations or other risks or to adjust long or short investment exposure to one or more asset classes or issuers.

As an alternative to investing directly in securities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives (e.g., selling put options on securities) and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund's foreign currency exposure may differ from the currency exposure of its securities. In addition, the Fund may lend its portfolio securities.

The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund may have gross investment exposures in excess of its net assets (i.e., the Fund may be leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

The Fund may gain exposure to commodities and some other asset classes by investing through a wholly-owned subsidiary advised by GMO, which does not receive management or other fees for its services. The subsidiary invests primarily in commodity-related derivatives and fixed income securities but also may gain exposure to any other investment in which the Fund is permitted to invest directly. References in this Prospectus to the Fund may refer to actions undertaken by the subsidiary as well as the Fund. The Fund does not invest directly in commodities and commodity-related derivatives, but may do so indirectly through its subsidiary company (or otherwise).

In seeking to achieve the Fund's investment objective, GMO may invest a significant portion of the Fund's net assets in cash and cash equivalents. GMO would not consider such investments to be "temporary defensive positions."

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund's shares changes with the value of the Fund's investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund's investments in its wholly-owned subsidiary and in any underlying funds in which it invests. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in its wholly-owned subsidiary and in any underlying funds, see "Description of Principal Risks."

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market's uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund's foreign currency holdings and investments denominated in foreign currencies.

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer's, guarantor's, or obligor's failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin, or otherwise honor its obligations.

• Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund's investments.

• Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. A merger arbitrage transaction can fail for many reasons, including regulatory and antitrust restrictions, political motivations, industry weakness, stock specific events, failed financings, and general market declines. When merger activity is low, GMO may be unable to identify enough opportunities to provide sufficient diversification. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated. The Fund's investments in derivatives or short sales of securities to hedge or otherwise adjust investment exposure in connection with a merger arbitrage transaction may not perform as expected or may otherwise reduce the Fund's gains or increase its losses.

• Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund's shares to decline or fluctuate in a rapid and unpredictable manner.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in its wholly-owned subsidiary and in any underlying funds in which it invests (including ETFs), including the risk that its wholly-owned subsidiary and those underlying funds will not perform as expected.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Year Index and the Consumer Price Index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns
Years Ending December 31

Highest Quarter: 6.01% (1Q2013)
Lowest Quarter: – 7.90% (3Q2015)
Year-to-Date (as of 3/31/16): 0.08%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Implementation Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
GMO Implementation Fund		(5.01%)			5.55%	Mar. 01, 2012
GMO Implementation Fund | Return After Taxes on Distributions	[1]	(5.01%)			5.55%	Mar. 01, 2012
GMO Implementation Fund | Return After Taxes on Distributions and Sale of Fund Shares	[1]	(2.84%)			4.30%	Mar. 01, 2012
Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes)		0.72%			1.06%	Mar. 01, 2012
Consumer Price Index (reflects no deduction for fees, expenses, or taxes)		(0.52%)			0.55%	Mar. 01, 2012

[1] The amount includes interest expense and dividend expenses incurred by the Fund as a result of short sales. “Other expenses” (before addition of interest expense and dividend expenses on short sales), interest expense and dividend expenses on short sales were approximately 0.05%, 0.01% and 0.06%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC (“GMO”) has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees, and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[3] after expense reimbursement

[1] After-tax returns do not reflect distributions made by the Fund for all periods prior to July 1, 2015, the date on which the Fund elected to be treated as a corporation for U.S. federal income purposes. Further, as described in “Distributions and Taxes,” the Fund intends to elect to be treated and to qualify and be treated each year as a regulated investment company under Subchapter M of the Internal Revenue Code of 1986, as amended, for U.S. federal income tax purposes.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Implementation Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO IMPLEMENTATION FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Positive total return, not “relative return.”
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (including the accounts of the Fund’s wholly-owned subsidiary, GMO Implementation SPC Ltd., and excluding short-term investments) was 127% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	127.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other funds or accounts managed by GMO. Accordingly, the Fund is not a standalone investment. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to determine the Fund's strategic direction. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. The factors GMO considers and investment methods GMO uses can change over time. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. Depending on GMO's outlook, the Fund may have exposure to any asset class (e.g., non-U.S. equity, U.S. equity, emerging country equity, emerging country debt, non-U.S. fixed income, U.S. fixed income, real estate, and commodities) and at times may be substantially invested in a single asset class. The Fund may invest in securities of companies of any market capitalization. In addition, the Fund is not limited in how much it may invest in any market, and it may invest all of its assets in the securities of a limited number of companies in a single country and/or capitalization range. The Fund may invest a significant portion of its assets in the securities of issuers in industries that are subject to the same or similar risk factors. To the extent the Fund invests in fixed income securities, it may have significant exposure to fixed income instruments of any credit quality, including those that are below investment grade (commonly referred to as "junk bonds") and having any maturity or duration. The Fund also may have exposure to short sales. GMO's ability to shift investments among asset classes is not subject to any limits. The Fund may engage in transactions in which it purchases securities at prices below the value of the consideration GMO expects to be paid for them upon consummation of a proposed merger, exchange offer, tender offer, or other similar transaction ("merger arbitrage transactions"). The purchase price may substantially exceed the market price of the securities before the announcement of the transaction. In conjunction with merger arbitrage transactions, the Fund may invest in derivatives or sell securities short in an effort to protect against market fluctuations or other risks or to adjust long or short investment exposure to one or more asset classes or issuers. As an alternative to investing directly in securities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives (e.g., selling put options on securities) and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund's foreign currency exposure may differ from the currency exposure of its securities. In addition, the Fund may lend its portfolio securities. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund may have gross investment exposures in excess of its net assets (i.e., the Fund may be leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices. The Fund may gain exposure to commodities and some other asset classes by investing through a wholly-owned subsidiary advised by GMO, which does not receive management or other fees for its services. The subsidiary invests primarily in commodity-related derivatives and fixed income securities but also may gain exposure to any other investment in which the Fund is permitted to invest directly. References in this Prospectus to the Fund may refer to actions undertaken by the subsidiary as well as the Fund. The Fund does not invest directly in commodities and commodity-related derivatives, but may do so indirectly through its subsidiary company (or otherwise). In seeking to achieve the Fund's investment objective, GMO may invest a significant portion of the Fund's net assets in cash and cash equivalents. GMO would not consider such investments to be "temporary defensive positions." The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund's shares changes with the value of the Fund's investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund's investments in its wholly-owned subsidiary and in any underlying funds in which it invests. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in its wholly-owned subsidiary and in any underlying funds, see "Description of Principal Risks." Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO's incorrect assessment of the equity's fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund's shares. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market's uncertainty about the value of a fixed income investment (or class of fixed income investments). Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Management and Operational Risk – The Fund runs the risk that GMO's investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO's models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund's performance. The Fund also runs the risk that GMO's assessment of an investment (including a company's fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO's or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Illiquidity Risk – Low trading volume, lack of a market maker, large position size or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund's foreign currency holdings and investments denominated in foreign currencies. Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer's, guarantor's, or obligor's failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund's securities will be unable or unwilling to make timely settlement payments, return the Fund's margin, or otherwise honor its obligations. Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund's losses when the value of its investments (including derivatives) declines. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund's investments. Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. A merger arbitrage transaction can fail for many reasons, including regulatory and antitrust restrictions, political motivations, industry weakness, stock specific events, failed financings, and general market declines. When merger activity is low, GMO may be unable to identify enough opportunities to provide sufficient diversification. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated. The Fund's investments in derivatives or short sales of securities to hedge or otherwise adjust investment exposure in connection with a merger arbitrage transaction may not perform as expected or may otherwise reduce the Fund's gains or increase its losses. Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund's shares to decline or fluctuate in a rapid and unpredictable manner. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund's operations. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in its wholly-owned subsidiary and in any underlying funds in which it invests (including ETFs), including the risk that its wholly-owned subsidiary and those underlying funds will not perform as expected.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Year Index and the Consumer Price Index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Year Index and the Consumer Price Index.
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 6.01% (1Q2013) Lowest Quarter: – 7.90% (3Q2015) Year-to-Date (as of 3/31/16): 0.08%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Implementation Fund | GMO Implementation Fund
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.20%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.20%
Management fee	rr_ManagementFeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.12%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.12%
Expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.07%	[3]
1 Year	rr_ExpenseExampleYear01	$ 48
3 Years	rr_ExpenseExampleYear03	77
5 Years	rr_ExpenseExampleYear05	108
10 Years	rr_ExpenseExampleYear10	201
1 Year	rr_ExpenseExampleNoRedemptionYear01	27
3 Years	rr_ExpenseExampleNoRedemptionYear03	54
5 Years	rr_ExpenseExampleNoRedemptionYear05	83
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 168
2013	rr_AnnualReturn2013	17.10%
2014	rr_AnnualReturn2014	2.21%
2015	rr_AnnualReturn2015	(4.63%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.08%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2013
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	6.01%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(7.90%)
1 Year	rr_AverageAnnualReturnYear01	(5.01%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	5.55%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2012
GMO Implementation Fund | Return After Taxes on Distributions | GMO Implementation Fund
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(5.01%)	[4]
5 Years	rr_AverageAnnualReturnYear05		[4]
10 Years	rr_AverageAnnualReturnYear10		[4]
Incept.	rr_AverageAnnualReturnSinceInception	5.55%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2012	[4]
GMO Implementation Fund | Return After Taxes on Distributions and Sale of Fund Shares | GMO Implementation Fund
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.84%)	[4]
5 Years	rr_AverageAnnualReturnYear05		[4]
10 Years	rr_AverageAnnualReturnYear10		[4]
Incept.	rr_AverageAnnualReturnSinceInception	4.30%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2012	[4]
GMO Implementation Fund | Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.72%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.06%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2012
GMO Implementation Fund | Consumer Price Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.52%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.55%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2012

[1] The amount includes interest expense and dividend expenses incurred by the Fund as a result of short sales. “Other expenses” (before addition of interest expense and dividend expenses on short sales), interest expense and dividend expenses on short sales were approximately 0.05%, 0.01% and 0.06%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC (“GMO”) has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees, and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[3] after expense reimbursement

[4] After-tax returns do not reflect distributions made by the Fund for all periods prior to July 1, 2015, the date on which the Fund elected to be treated as a corporation for U.S. federal income purposes. Further, as described in “Distributions and Taxes,” the Fund intends to elect to be treated and to qualify and be treated each year as a regulated investment company under Subchapter M of the Internal Revenue Code of 1986, as amended, for U.S. federal income tax purposes.

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GMO Risk Premium Fund

GMO RISK PREMIUM FUND

Investment objective

Total return.

Fees and expenses

The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees - GMO Risk Premium Fund	Class III	Class IV	Class V	Class VI
Purchase premium (as a percentage of amount invested)	0.15%	0.15%	0.15%	0.15%
Redemption fee (as a percentage of amount redeemed)	0.15%	0.15%	0.15%	0.15%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Risk Premium Fund		Class III	Class IV	Class V	Class VI
Management fee	[1]	0.45%	0.45%	0.45%	0.45%
Shareholder service fee	[1]	0.15%	0.10%	0.085%	0.055%
Other expenses		0.05%	0.05%	0.05%	0.05%
Total annual fund operating expenses		0.65%	0.60%	0.59%	0.56%
Expense reimbursement/waiver	[1]	(0.05%)	(0.05%)	(0.05%)	(0.05%)
Total annual fund operating expenses	[2]	0.60%	0.55%	0.54%	0.51%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example - GMO Risk Premium Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	92	235	390	842
Class IV	87	219	363	782
Class V	86	216	357	770
Class VI	83	206	341	734

If you do not sell your shares

Expense Example, No Redemption - GMO Risk Premium Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	76	218	372	819
Class IV	71	202	344	759
Class V	70	199	339	747
Class VI	67	189	322	711

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 0% of the average value of its portfolio.

Principal investment strategies

GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other funds or accounts managed by GMO. Accordingly, the Fund is not a standalone investment.

The Fund seeks to capture returns commensurate with the equity risk premium over a full market cycle with less sensitivity to equity valuations by selling (writing) put options on stock indices and by engaging in merger arbitrage strategies. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark.

The Fund primarily uses options by writing put options on U.S. and non-U.S. (e.g., Europe, United Kingdom, Japan, Hong Kong, Canada, and Australia) stock indices. While the Fund may write put options with any strike price or duration, the Fund generally writes put options with a strike price at or near the market price of the underlying asset and with a duration of one to three months. GMO determines the Fund's put-writing allocations by, among other things, comparing the liquidity available in each region's options markets against the opportunities available, focusing on patterns of information and assessing the relative attractiveness of each index. The Fund may have substantial exposures to relatively few U.S. and international stock indices. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

The Fund may purchase and write put and call options of any type, including options on global, regional and country stock indices and options on exchange-traded funds (ETFs). The Fund may purchase and write exchange-traded and over-the-counter (OTC) options, including options that are cash-settled as well as physically settled. The Fund may purchase and write options and other securities tied economically to any country in the world, including emerging countries. The Fund may invest in forward currency contracts to manage its currency exposure.

GMO expects that the Fund's written option positions typically will be fully collateralized at the time the Fund writes them. GMO, therefore, expects that the Fund will hold sufficient assets to cover the maximum possible loss the Fund might sustain upon the exercise of an option written by the Fund.

The Fund may invest in securities of companies of any market capitalization.

The factors GMO considers and investment methods GMO uses can change over time.

For collateral and cash management purposes, the Fund invests a substantial portion of its assets in shares of U.S. Treasury Fund, in U.S. Treasury bills and other highly rated securities, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – Because of the Fund’s emphasis on selling put options on stock indices, GMO generally expects the Fund’s net asset value to decline when those indices decline in value. The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. Also, the Fund’s investment strategies of writing put options on stock indices and engaging in merger arbitrage transactions can be expected to cause the Fund to underperform relative to those indices when those markets rise sharply.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from closing its option positions at desirable prices. The Fund’s ability to use options as part of its investment program depends on the liquidity of the options market. That market may not be liquid when the Fund seeks to close out an option position. If the Fund receives a redemption request and is unable to close out an option it has sold, the Fund may temporarily be leveraged in relation to its assets.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Focused Investment Risk – Because the Fund can have substantial exposure through a limited number of options contracts and/or merger arbitrage transactions and because the Fund’s exposures may relate to relatively few stock indices and/or merger arbitrage transactions, the Fund is subject to more risk than if the Fund’s investments were more diversified.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment (e.g., U.S. Treasury bills) can decline due to market-related factors, primarily rising interest rates.

• Credit Risk – Securities issued by the U.S. Treasury historically have presented minimal credit risk. However, events in 2011 led to a downgrade in the long-term credit rating of U.S. bonds by several major rating agencies and introduced greater uncertainty about the repayment by the United States of its obligations. A further credit rating downgrade could decrease, and a U.S. credit default would decrease, the value of the Fund’s investments and increase the volatility of the Fund’s portfolio.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. To the extent the Fund focuses its investments in the stock index of a particular region, adverse geopolitical and other events in that region could have a disproportionate impact on the Fund.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing the Fund’s annual total returns for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 5.12% (4Q2013)
Lowest Quarter: – 4.92% (4Q2014)
Year-to-Date (as of 3/31/16): – 2.46%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Risk Premium Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	6.16%			4.72%	Dec. 14, 2012
Class III | Return After Taxes on Distributions	3.55%			2.11%	Dec. 14, 2012
Class III | Return After Taxes on Distributions and Sale of Fund Shares	4.55%			2.84%	Dec. 14, 2012
Class III | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.87%)			9.86%	Dec. 14, 2012
Class IV	6.15%			4.69%	Dec. 17, 2012
Class IV | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.87%)			9.62%	Dec. 17, 2012
Class VI	6.25%			5.58%	Nov. 15, 2012
Class VI | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.87%)			11.61%	Nov. 15, 2012

[1] Grantham, Mayo, Van Otterloo & Co. LLC (“GMO”) has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund’s management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund’s direct or indirect investments in other series of GMO Trust (“GMO Funds”). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[2] after expense reimbursement/waiver

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Risk Premium Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO RISK PREMIUM FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 0% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	none
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other funds or accounts managed by GMO. Accordingly, the Fund is not a standalone investment. The Fund seeks to capture returns commensurate with the equity risk premium over a full market cycle with less sensitivity to equity valuations by selling (writing) put options on stock indices and by engaging in merger arbitrage strategies. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. The Fund primarily uses options by writing put options on U.S. and non-U.S. (e.g., Europe, United Kingdom, Japan, Hong Kong, Canada, and Australia) stock indices. While the Fund may write put options with any strike price or duration, the Fund generally writes put options with a strike price at or near the market price of the underlying asset and with a duration of one to three months. GMO determines the Fund's put-writing allocations by, among other things, comparing the liquidity available in each region's options markets against the opportunities available, focusing on patterns of information and assessing the relative attractiveness of each index. The Fund may have substantial exposures to relatively few U.S. and international stock indices. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices. The Fund may purchase and write put and call options of any type, including options on global, regional and country stock indices and options on exchange-traded funds (ETFs). The Fund may purchase and write exchange-traded and over-the-counter (OTC) options, including options that are cash-settled as well as physically settled. The Fund may purchase and write options and other securities tied economically to any country in the world, including emerging countries. The Fund may invest in forward currency contracts to manage its currency exposure. GMO expects that the Fund's written option positions typically will be fully collateralized at the time the Fund writes them. GMO, therefore, expects that the Fund will hold sufficient assets to cover the maximum possible loss the Fund might sustain upon the exercise of an option written by the Fund. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. For collateral and cash management purposes, the Fund invests a substantial portion of its assets in shares of U.S. Treasury Fund, in U.S. Treasury bills and other highly rated securities, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – Because of the Fund’s emphasis on selling put options on stock indices, GMO generally expects the Fund’s net asset value to decline when those indices decline in value. The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. Also, the Fund’s investment strategies of writing put options on stock indices and engaging in merger arbitrage transactions can be expected to cause the Fund to underperform relative to those indices when those markets rise sharply. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from closing its option positions at desirable prices. The Fund’s ability to use options as part of its investment program depends on the liquidity of the options market. That market may not be liquid when the Fund seeks to close out an option position. If the Fund receives a redemption request and is unable to close out an option it has sold, the Fund may temporarily be leveraged in relation to its assets. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Focused Investment Risk – Because the Fund can have substantial exposure through a limited number of options contracts and/or merger arbitrage transactions and because the Fund’s exposures may relate to relatively few stock indices and/or merger arbitrage transactions, the Fund is subject to more risk than if the Fund’s investments were more diversified. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies. Market Risk – Fixed Income Investments – The market price of a fixed income investment (e.g., U.S. Treasury bills) can decline due to market-related factors, primarily rising interest rates. Credit Risk – Securities issued by the U.S. Treasury historically have presented minimal credit risk. However, events in 2011 led to a downgrade in the long-term credit rating of U.S. bonds by several major rating agencies and introduced greater uncertainty about the repayment by the United States of its obligations. A further credit rating downgrade could decrease, and a U.S. credit default would decrease, the value of the Fund’s investments and increase the volatility of the Fund’s portfolio. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. To the extent the Fund focuses its investments in the stock index of a particular region, adverse geopolitical and other events in that region could have a disproportionate impact on the Fund. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing the Fund’s annual total returns for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing the Fund’s annual total returns for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 5.12% (4Q2013) Lowest Quarter: – 4.92% (4Q2014) Year-to-Date (as of 3/31/16): – 2.46%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Risk Premium Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.15%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.15%
Management fee	rr_ManagementFeesOverAssets	0.45%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.05%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.65%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.60%	[2]
1 Year	rr_ExpenseExampleYear01	$ 92
3 Years	rr_ExpenseExampleYear03	235
5 Years	rr_ExpenseExampleYear05	390
10 Years	rr_ExpenseExampleYear10	842
1 Year	rr_ExpenseExampleNoRedemptionYear01	76
3 Years	rr_ExpenseExampleNoRedemptionYear03	218
5 Years	rr_ExpenseExampleNoRedemptionYear05	372
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 819
2013	rr_AnnualReturn2013	7.75%
2014	rr_AnnualReturn2014	(0.19%)
2015	rr_AnnualReturn2015	6.48%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(2.46%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2013
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	5.12%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2014
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(4.92%)
1 Year	rr_AverageAnnualReturnYear01	6.16%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	4.72%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 14, 2012
GMO Risk Premium Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.15%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.15%
Management fee	rr_ManagementFeesOverAssets	0.45%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.05%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.60%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.55%	[2]
1 Year	rr_ExpenseExampleYear01	$ 87
3 Years	rr_ExpenseExampleYear03	219
5 Years	rr_ExpenseExampleYear05	363
10 Years	rr_ExpenseExampleYear10	782
1 Year	rr_ExpenseExampleNoRedemptionYear01	71
3 Years	rr_ExpenseExampleNoRedemptionYear03	202
5 Years	rr_ExpenseExampleNoRedemptionYear05	344
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 759
1 Year	rr_AverageAnnualReturnYear01	6.15%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	4.69%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 17, 2012
GMO Risk Premium Fund | Class V
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.15%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.15%
Management fee	rr_ManagementFeesOverAssets	0.45%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.085%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.05%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.59%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.54%	[2]
1 Year	rr_ExpenseExampleYear01	$ 86
3 Years	rr_ExpenseExampleYear03	216
5 Years	rr_ExpenseExampleYear05	357
10 Years	rr_ExpenseExampleYear10	770
1 Year	rr_ExpenseExampleNoRedemptionYear01	70
3 Years	rr_ExpenseExampleNoRedemptionYear03	199
5 Years	rr_ExpenseExampleNoRedemptionYear05	339
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 747
GMO Risk Premium Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.15%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.15%
Management fee	rr_ManagementFeesOverAssets	0.45%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.05%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.56%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.51%	[2]
1 Year	rr_ExpenseExampleYear01	$ 83
3 Years	rr_ExpenseExampleYear03	206
5 Years	rr_ExpenseExampleYear05	341
10 Years	rr_ExpenseExampleYear10	734
1 Year	rr_ExpenseExampleNoRedemptionYear01	67
3 Years	rr_ExpenseExampleNoRedemptionYear03	189
5 Years	rr_ExpenseExampleNoRedemptionYear05	322
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 711
1 Year	rr_AverageAnnualReturnYear01	6.25%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	5.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 15, 2012
GMO Risk Premium Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	3.55%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	2.11%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 14, 2012
GMO Risk Premium Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.55%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	2.84%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 14, 2012
GMO Risk Premium Fund | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.87%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	9.86%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 14, 2012
GMO Risk Premium Fund | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.87%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	9.62%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 17, 2012
GMO Risk Premium Fund | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments) | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.87%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	11.61%
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 15, 2012

[1] Grantham, Mayo, Van Otterloo & Co. LLC (“GMO”) has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund’s management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund’s direct or indirect investments in other series of GMO Trust (“GMO Funds”). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[2] after expense reimbursement/waiver

XML

GMO Special Opportunities Fund

GMO SPECIAL OPPORTUNITIES FUND

Investment objective

Positive total return.

Fees and expenses

The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees - GMO Special Opportunities Fund	Class III	Class IV	Class V	Class VI
Purchase premium (as a percentage of amount invested)	0.50%	0.50%	0.50%	0.50%
Redemption fee (as a percentage of amount redeemed)	0.50%	0.50%	0.50%	0.50%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - GMO Special Opportunities Fund		Class III	Class IV	Class V	Class VI
Management fee	[1]	1.10%	1.10%	1.10%	1.10%
Shareholder service fee	[1]	0.15%	0.10%	0.085%	0.055%
Other expenses		0.14%	0.14%	0.14%	0.14%
Acquired fund fees and expenses (underlying fund expenses)	[2]	0.04%	0.04%	0.04%	0.04%
Total annual fund operating expenses		1.43%	1.38%	1.37%	1.34%
Expense reimbursement/waiver	[1]	none	none	none	none
Total annual fund operating expenses	[3]	1.43%	1.38%	1.37%	1.34%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example - GMO Special Opportunities Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	246	555	887	1,825
Class IV	241	540	861	1,770
Class V	240	537	856	1,759
Class VI	237	528	840	1,726

If you do not sell your shares

Expense Example, No Redemption - GMO Special Opportunities Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
Class III	195	500	828	1,755
Class IV	190	485	801	1,699
Class V	189	482	796	1,688
Class VI	186	472	780	1,655

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (including the accounts of the Fund’s wholly-owned subsidiary, GMO Special Opportunities SPC Ltd., and excluding short-term investments) was 69% of the average value of its portfolio.

Principal investment strategies

GMO generally uses a fundamental approach to identify investments that are, in GMO's judgment, trading below their fundamental fair (or intrinsic) value. GMO expects that the Fund's portfolio will consist of a limited number of investments. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. The factors GMO considers and investment methods GMO uses can change over time.

The Fund may have long or short exposure to non-U.S. and U.S. equities (which may include emerging country equities and equities of any market capitalization), non-U.S. and U.S. fixed income instruments (which may include asset-backed securities and other fixed income instruments of any credit quality, including those that are below investment grade (commonly referred to as "junk bonds"), including distressed and defaulted debt securities, and having any maturity or duration), currencies, and, from time to time, other alternative instruments (e.g., instruments that seek exposure to, or reduce risks of, market volatility). The Fund may engage in merger arbitrage transactions.

The Fund is not restricted in its exposure to any particular asset class and at times may be substantially exposed (long or short) to a single asset class (e.g., equities or fixed income securities). In addition, the Fund is not restricted in its exposure (long or short) to any particular market. The Fund may have substantial exposure (long or short) to securities of companies in a particular country or type of country (e.g., emerging countries). The Fund could be subject to material losses from a single investment.

In pursuing its investment objective, the Fund may (but is not obligated to) invest in a wide variety of exchange-traded and over-the-counter (OTC) derivatives, including, without limitation, reverse repurchase agreements, options, futures, swap contracts (such as swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, credit default swaps, variance swaps, commodity swaps, inflation swaps, and other types of swaps), swaptions, and foreign currency derivative transactions. In addition, the Fund may lend its portfolio securities. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund may have gross investment exposures in excess of its net assets (i.e., the Fund may be leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices.

The Fund may gain exposure to commodities and some other assets by investing through a wholly-owned subsidiary advised by GMO, which does not receive management or other fees for its services. The subsidiary invests primarily in commodity-related derivatives and fixed income securities but also may gain exposure to any other investment in which the Fund is permitted to invest directly. References in this Prospectus to the Fund may refer to actions undertaken by the subsidiary as well as the Fund. The Fund does not invest directly in commodities and commodity-related derivatives, but may do so indirectly through its subsidiary company (or otherwise).

In seeking to achieve the Fund's investment objective, GMO may invest a significant portion of the Fund's net assets in cash and cash equivalents. GMO would not consider such investments to be "temporary defensive positions."

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in its wholly-owned subsidiary and in any underlying funds in which it invests. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in its wholly-owned subsidiary and in any underlying funds, see “Description of Principal Risks.”

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. Because the Fund normally does not take temporary defensive positions, declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Investments in distressed or defaulted or other low quality debt securities generally are considered speculative and may involve substantial risks not normally associated with investments in higher quality securities, including adverse business, financial or economic conditions that lead to payment defaults and insolvency proceedings on the part of their issuers. In particular, distressed or defaulted obligations might be repaid, if at all, only after lengthy workout or bankruptcy proceedings, during which the issuer might not make any interest or other payments, and the Fund may incur additional expenses to seek recovery. If GMO’s assessment of the eventual recovery value of a distressed or defaulted debt security proves incorrect, the Fund may lose a substantial portion or all of its investment or may be required to accept cash or instruments worth less than its original investment.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could reduce the value of the Fund’s investments.

• Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin, or otherwise honor its obligations.

• Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in its wholly-owned subsidiary and in any underlying funds in which it invests, including the risk that its wholly-owned subsidiary or those underlying funds will not perform as expected.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Years Index and the Consumer Price Index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class VI Shares
Years Ending December 31

Highest Quarter: 3.21% (4Q2015)
Lowest Quarter: – 3.83% (3Q2015)
Year-to-Date (as of 3/31/16): 1.28%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Special Opportunities Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class VI	1.23%			(0.59%)	Jul. 28, 2014
Class VI | Return After Taxes on Distributions	0.51%			(1.10%)	Jul. 28, 2014
Class VI | Return After Taxes on Distributions and Sale of Fund Shares	1.00%			(0.56%)	Jul. 28, 2014
Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes)	(0.52%)			(2.42%)	Jul. 28, 2014
Consumer Price Index (reflects no deduction for fees, expenses, or taxes)	0.72%			(0.01%)	Jul. 28, 2014

[1] Grantham, Mayo, Van Otterloo & Co. LLC (“GMO”) has contractually agreed to reimburse the Fund for the portion of its “Specified Operating Expenses” (as defined below) that exceeds 0.10% of the Fund’s average daily net assets. “Specified Operating Expenses” means only the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund’s management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund’s direct or indirect investments in other series of GMO Trust (“GMO Funds”). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[2] These indirect expenses include commissions paid to brokers by the Fund for executing transactions in unaffiliated underlying funds (“transaction fees”). Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.03% and 0.01%, respectively.

[3] after expense reimbursement/waiver (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Special Opportunities Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO SPECIAL OPPORTUNITIES FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Positive total return.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (including the accounts of the Fund’s wholly-owned subsidiary, GMO Special Opportunities SPC Ltd., and excluding short-term investments) was 69% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	69.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO generally uses a fundamental approach to identify investments that are, in GMO's judgment, trading below their fundamental fair (or intrinsic) value. GMO expects that the Fund's portfolio will consist of a limited number of investments. GMO does not manage the Fund to, or control the Fund's risk relative to, any securities index or securities benchmark. The factors GMO considers and investment methods GMO uses can change over time. The Fund may have long or short exposure to non-U.S. and U.S. equities (which may include emerging country equities and equities of any market capitalization), non-U.S. and U.S. fixed income instruments (which may include asset-backed securities and other fixed income instruments of any credit quality, including those that are below investment grade (commonly referred to as "junk bonds"), including distressed and defaulted debt securities, and having any maturity or duration), currencies, and, from time to time, other alternative instruments (e.g., instruments that seek exposure to, or reduce risks of, market volatility). The Fund may engage in merger arbitrage transactions. The Fund is not restricted in its exposure to any particular asset class and at times may be substantially exposed (long or short) to a single asset class (e.g., equities or fixed income securities). In addition, the Fund is not restricted in its exposure (long or short) to any particular market. The Fund may have substantial exposure (long or short) to securities of companies in a particular country or type of country (e.g., emerging countries). The Fund could be subject to material losses from a single investment. In pursuing its investment objective, the Fund may (but is not obligated to) invest in a wide variety of exchange-traded and over-the-counter (OTC) derivatives, including, without limitation, reverse repurchase agreements, options, futures, swap contracts (such as swaps on securities and securities indices, total return swaps, interest rate swaps, currency swaps, cross currency basis swaps, credit default swaps, variance swaps, commodity swaps, inflation swaps, and other types of swaps), swaptions, and foreign currency derivative transactions. In addition, the Fund may lend its portfolio securities. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund may have gross investment exposures in excess of its net assets (i.e., the Fund may be leveraged) and therefore is subject to heightened risk of loss. The Fund's performance can depend substantially, if not primarily, on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices. The Fund may gain exposure to commodities and some other assets by investing through a wholly-owned subsidiary advised by GMO, which does not receive management or other fees for its services. The subsidiary invests primarily in commodity-related derivatives and fixed income securities but also may gain exposure to any other investment in which the Fund is permitted to invest directly. References in this Prospectus to the Fund may refer to actions undertaken by the subsidiary as well as the Fund. The Fund does not invest directly in commodities and commodity-related derivatives, but may do so indirectly through its subsidiary company (or otherwise). In seeking to achieve the Fund's investment objective, GMO may invest a significant portion of the Fund's net assets in cash and cash equivalents. GMO would not consider such investments to be "temporary defensive positions." The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in its wholly-owned subsidiary and in any underlying funds in which it invests. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in its wholly-owned subsidiary and in any underlying funds, see “Description of Principal Risks.” Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. Because the Fund normally does not take temporary defensive positions, declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Investments in distressed or defaulted or other low quality debt securities generally are considered speculative and may involve substantial risks not normally associated with investments in higher quality securities, including adverse business, financial or economic conditions that lead to payment defaults and insolvency proceedings on the part of their issuers. In particular, distressed or defaulted obligations might be repaid, if at all, only after lengthy workout or bankruptcy proceedings, during which the issuer might not make any interest or other payments, and the Fund may incur additional expenses to seek recovery. If GMO’s assessment of the eventual recovery value of a distressed or defaulted debt security proves incorrect, the Fund may lose a substantial portion or all of its investment or may be required to accept cash or instruments worth less than its original investment. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Illiquidity Risk – Low trading volume, lack of a market maker, large position size or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could reduce the value of the Fund’s investments. Focused Investment Risk – Investments focused in a limited number of countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin, or otherwise honor its obligations. Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in its wholly-owned subsidiary and in any underlying funds in which it invests, including the risk that its wholly-owned subsidiary or those underlying funds will not perform as expected.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund's performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Years Index and the Consumer Price Index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's annual total returns from year to year for the periods indicated and by comparing the Fund's average annual total returns for different calendar periods with those of the Barclays U.S. Treasury Inflation Notes: 1-10 Years Index and the Consumer Price Index.
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class VI Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 3.21% (4Q2015) Lowest Quarter: – 3.83% (3Q2015) Year-to-Date (as of 3/31/16): 1.28%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Special Opportunities Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.50%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.50%
Management fee	rr_ManagementFeesOverAssets	1.10%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.43%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.43%	[3]
1 Year	rr_ExpenseExampleYear01	$ 246
3 Years	rr_ExpenseExampleYear03	555
5 Years	rr_ExpenseExampleYear05	887
10 Years	rr_ExpenseExampleYear10	1,825
1 Year	rr_ExpenseExampleNoRedemptionYear01	195
3 Years	rr_ExpenseExampleNoRedemptionYear03	500
5 Years	rr_ExpenseExampleNoRedemptionYear05	828
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,755
GMO Special Opportunities Fund | Class IV
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.50%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.50%
Management fee	rr_ManagementFeesOverAssets	1.10%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.10%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.38%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.38%	[3]
1 Year	rr_ExpenseExampleYear01	$ 241
3 Years	rr_ExpenseExampleYear03	540
5 Years	rr_ExpenseExampleYear05	861
10 Years	rr_ExpenseExampleYear10	1,770
1 Year	rr_ExpenseExampleNoRedemptionYear01	190
3 Years	rr_ExpenseExampleNoRedemptionYear03	485
5 Years	rr_ExpenseExampleNoRedemptionYear05	801
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,699
GMO Special Opportunities Fund | Class V
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.50%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.50%
Management fee	rr_ManagementFeesOverAssets	1.10%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.085%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.37%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.37%	[3]
1 Year	rr_ExpenseExampleYear01	$ 240
3 Years	rr_ExpenseExampleYear03	537
5 Years	rr_ExpenseExampleYear05	856
10 Years	rr_ExpenseExampleYear10	1,759
1 Year	rr_ExpenseExampleNoRedemptionYear01	189
3 Years	rr_ExpenseExampleNoRedemptionYear03	482
5 Years	rr_ExpenseExampleNoRedemptionYear05	796
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,688
GMO Special Opportunities Fund | Class VI
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.50%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.50%
Management fee	rr_ManagementFeesOverAssets	1.10%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.055%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.34%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	1.34%	[3]
1 Year	rr_ExpenseExampleYear01	$ 237
3 Years	rr_ExpenseExampleYear03	528
5 Years	rr_ExpenseExampleYear05	840
10 Years	rr_ExpenseExampleYear10	1,726
1 Year	rr_ExpenseExampleNoRedemptionYear01	186
3 Years	rr_ExpenseExampleNoRedemptionYear03	472
5 Years	rr_ExpenseExampleNoRedemptionYear05	780
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,655
2015	rr_AnnualReturn2015	2.25%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	1.28%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2015
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	3.21%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(3.83%)
1 Year	rr_AverageAnnualReturnYear01	1.23%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(0.59%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 28, 2014
GMO Special Opportunities Fund | Return After Taxes on Distributions | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.51%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(1.10%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 28, 2014
GMO Special Opportunities Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.00%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(0.56%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 28, 2014
GMO Special Opportunities Fund | Barclays U.S. Treasury Inflation Notes: 1-10 Year Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.52%)
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(2.42%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 28, 2014
GMO Special Opportunities Fund | Consumer Price Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.72%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	(0.01%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 28, 2014

[1] Grantham, Mayo, Van Otterloo & Co. LLC (“GMO”) has contractually agreed to reimburse the Fund for the portion of its “Specified Operating Expenses” (as defined below) that exceeds 0.10% of the Fund’s average daily net assets. “Specified Operating Expenses” means only the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund’s management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund’s direct or indirect investments in other series of GMO Trust (“GMO Funds”). Management fees and shareholder service fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund’s Board of Trustees.

[2] These indirect expenses include commissions paid to brokers by the Fund for executing transactions in unaffiliated underlying funds (“transaction fees”). Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.03% and 0.01%, respectively.

[3] after expense reimbursement/waiver (Fund and underlying fund expenses)

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GMO Strategic Opportunities Allocation Fund

GMO STRATEGIC OPPORTUNITIES ALLOCATION FUND

Investment objective

Total return greater than that of its benchmark, the GMO Strategic Opportunities Allocation Index, an internally maintained composite index computed by GMO, consisting of 75% MSCI World Index (MSCI Standard Index Series) and 25% Barclays U.S. Aggregate Index.

Fees and expenses

The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees	GMO Strategic Opportunities Allocation Fund Class III
Purchase premium (as a percentage of amount invested)	0.20%
Redemption fee (as a percentage of amount redeemed)	0.20%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Strategic Opportunities Allocation Fund Class III
Management fee	none
Shareholder service fee	none
Other expenses	0.01%
Acquired fund fees and expenses (underlying fund expenses)	0.55%	[1]
Total annual fund operating expenses	0.56%
Expense reimbursement	(0.01%)	[2]
Total annual fund operating expenses	0.55%	[3]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Strategic Opportunities Allocation Fund | Class III | USD ($)	97	227	369	783

If you do not sell your shares

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Strategic Opportunities Allocation Fund | Class III | USD ($)	76	205	345	753

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 65% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 39% of the average value of its portfolio.

Principal investment strategies

GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other accounts managed by GMO. Accordingly, the Fund is not a standalone investment.

The Fund is a fund of funds and invests primarily in shares of other series of GMO Trust (collectively, the "underlying GMO Funds"), which may include the Equity Funds, the Fixed Income Funds, the Implementation Funds, and SGM Major Markets Fund (see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Asset Allocation Funds"). The Fund also may invest directly in securities (including other underlying funds) and derivatives.

The Fund is permitted to invest in any asset class, including, for example, U.S. and non-U.S. equities (including emerging country equities), U.S. and non-U.S. fixed income securities of any credit quality, including below investment grade securities (commonly referred to as "junk bonds") (including emerging country debt securities) and commodities. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The Fund may invest in securities of companies of any market capitalization.

GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to select the underlying GMO Funds in which the Fund invests and to decide how much to invest in each. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund's holdings of the underlying GMO Funds in response to changes in GMO's investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund's investments. The factors GMO considers and investment methods GMO uses can change over time.

The Fund also may invest in money market funds unaffiliated with GMO or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.”

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries.

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments).

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Futures Contracts Risk – The risk of loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile and the use of futures contracts may increase the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time and the Fund might be unable to effect closing transactions to terminate its exposure to the contract. If the Fund uses futures contracts for hedging purposes, it runs the risk of imperfect correlation between changes in the prices of the contracts and changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are the subject of the hedge. In addition, the Fund may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts may be less liquid and more volatile than U.S. contracts.

• Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee.

• Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner.

• Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of broad-based indices and the Fund’s benchmark (which is a composite index computed by GMO). Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 11.73% (2Q2009)
Lowest Quarter: – 10.19% (4Q2008)
Year-to-Date (as of 3/31/16): 2.65%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Strategic Opportunities Allocation Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
Class III	(5.76%)	5.94%	5.74%	6.35%	May 31, 2005
Class III | Return After Taxes on Distributions	(8.02%)	3.97%	3.92%	4.56%	May 31, 2005
Class III | Return After Taxes on Distributions and Sale of Fund Shares	(1.87%)	4.63%	4.35%	4.87%	May 31, 2005
MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)	(0.87%)	7.59%	4.98%	5.75%	May 31, 2005
Barclays U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes)	0.55%	3.25%	4.52%	4.31%	May 31, 2005
GMO Strategic Opportunities Allocation Index (Fund benchmark)	(0.33%)	6.67%	5.14%	5.65%	May 31, 2005

[1] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.49%, less than 0.01%, and 0.06%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Strategic Opportunities Allocation Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO STRATEGIC OPPORTUNITIES ALLOCATION FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return greater than that of its benchmark, the GMO Strategic Opportunities Allocation Index, an internally maintained composite index computed by GMO, consisting of 75% MSCI World Index (MSCI Standard Index Series) and 25% Barclays U.S. Aggregate Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 65% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 39% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	65.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense reimbursement noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other accounts managed by GMO. Accordingly, the Fund is not a standalone investment. The Fund is a fund of funds and invests primarily in shares of other series of GMO Trust (collectively, the "underlying GMO Funds"), which may include the Equity Funds, the Fixed Income Funds, the Implementation Funds, and SGM Major Markets Fund (see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Asset Allocation Funds"). The Fund also may invest directly in securities (including other underlying funds) and derivatives. The Fund is permitted to invest in any asset class, including, for example, U.S. and non-U.S. equities (including emerging country equities), U.S. and non-U.S. fixed income securities of any credit quality, including below investment grade securities (commonly referred to as "junk bonds") (including emerging country debt securities) and commodities. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. The Fund may invest in securities of companies of any market capitalization. GMO uses its multi-year forecasts of returns among asset classes, together with its assessment of the relative risks of such asset classes, to select the underlying GMO Funds in which the Fund invests and to decide how much to invest in each. An important component of those forecasts is GMO's expectation that valuations ultimately revert to their fundamental fair (or intrinsic) value. GMO changes the Fund's holdings of the underlying GMO Funds in response to changes in GMO's investment outlook and market valuations and may use redemptions or purchases of Fund shares to rebalance the Fund's investments. The factors GMO considers and investment methods GMO uses can change over time. The Fund also may invest in money market funds unaffiliated with GMO or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. References to investments include those held directly by the Fund and indirectly through the Fund’s investments in underlying funds (including underlying GMO Funds). Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, including those risks to which the Fund is exposed as a result of its investments in the underlying funds, see “Description of Principal Risks.” Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If an underlying fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. An underlying fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity stemming from the market’s uncertainty about the value of a fixed income investment (or class of fixed income investments). Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Futures Contracts Risk – The risk of loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile and the use of futures contracts may increase the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time and the Fund might be unable to effect closing transactions to terminate its exposure to the contract. If the Fund uses futures contracts for hedging purposes, it runs the risk of imperfect correlation between changes in the prices of the contracts and changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are the subject of the hedge. In addition, the Fund may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts may be less liquid and more volatile than U.S. contracts. Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment or the obligor of an obligation underlying an asset-backed security will be unable or unwilling to satisfy its obligation to pay principal and interest or otherwise to honor its obligations in a timely manner. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligor’s failure to meet its payment obligations, or in anticipation of such failure. Below investment grade securities have speculative characteristics, and changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those securities to make principal and interest payments than is the case with issuers of investment grade securities. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of foreign currency holdings and investments denominated in foreign currencies. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds (including underlying GMO Funds) in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses. The fees and expenses associated with an investment in the Fund are less predictable than those associated with an investment in funds that charge a fixed management fee. Commodities Risk – Commodity prices can be extremely volatile, and exposure to commodities can cause the net asset value of the Fund’s shares to decline or fluctuate in a rapid and unpredictable manner. Merger Arbitrage Risk – If the Fund purchases securities in anticipation of a proposed merger, exchange offer, tender offer, or other similar transaction and that transaction later appears unlikely to be consummated or, in fact, is not consummated or is delayed, the market prices of the securities purchased by the Fund may decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, as the losses in failed transactions often far exceed the gains in successful transactions. Merger arbitrage strategies are subject to the risk of overall market movements, and the Fund may experience losses even if a transaction is consummated. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund or an underlying fund from selling particular securities or closing derivative positions at desirable prices. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Market Risk – Asset-Backed Securities – The market price of fixed income investments with complex structures, such as asset-backed securities, can decline due to a variety of factors, including market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, the deal structure, the creditworthiness of any credit-support provider, and the reliability of various other service providers with access to the payment stream), and a problem in any one of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive at the time the Fund purchased the asset-backed security. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor), the Fund is subject to the risk that a redemption by that shareholder of all or a large portion of its Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Some of the underlying funds are non-diversified investment companies under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by those underlying funds may affect the performance of those underlying funds more than if they were diversified investment companies.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of broad-based indices and the Fund’s benchmark (which is a composite index computed by GMO). Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of broad-based indices and the Fund’s benchmark (which is a composite index computed by GMO).
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 11.73% (2Q2009) Lowest Quarter: – 10.19% (4Q2008) Year-to-Date (as of 3/31/16): 2.65%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Strategic Opportunities Allocation Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.20%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.20%
Management fee	rr_ManagementFeesOverAssets	none
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.01%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.55%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.56%
Expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.55%	[3]
1 Year	rr_ExpenseExampleYear01	$ 97
3 Years	rr_ExpenseExampleYear03	227
5 Years	rr_ExpenseExampleYear05	369
10 Years	rr_ExpenseExampleYear10	783
1 Year	rr_ExpenseExampleNoRedemptionYear01	76
3 Years	rr_ExpenseExampleNoRedemptionYear03	205
5 Years	rr_ExpenseExampleNoRedemptionYear05	345
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 753
2006	rr_AnnualReturn2006	16.77%
2007	rr_AnnualReturn2007	9.07%
2008	rr_AnnualReturn2008	(21.40%)
2009	rr_AnnualReturn2009	21.13%
2010	rr_AnnualReturn2010	7.96%
2011	rr_AnnualReturn2011	2.21%
2012	rr_AnnualReturn2012	13.23%
2013	rr_AnnualReturn2013	19.95%
2014	rr_AnnualReturn2014	2.02%
2015	rr_AnnualReturn2015	(5.39%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	2.65%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	11.73%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(10.19%)
1 Year	rr_AverageAnnualReturnYear01	(5.76%)
5 Years	rr_AverageAnnualReturnYear05	5.94%
10 Years	rr_AverageAnnualReturnYear10	5.74%
Incept.	rr_AverageAnnualReturnSinceInception	6.35%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 31, 2005
GMO Strategic Opportunities Allocation Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(8.02%)
5 Years	rr_AverageAnnualReturnYear05	3.97%
10 Years	rr_AverageAnnualReturnYear10	3.92%
Incept.	rr_AverageAnnualReturnSinceInception	4.56%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 31, 2005
GMO Strategic Opportunities Allocation Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(1.87%)
5 Years	rr_AverageAnnualReturnYear05	4.63%
10 Years	rr_AverageAnnualReturnYear10	4.35%
Incept.	rr_AverageAnnualReturnSinceInception	4.87%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 31, 2005
GMO Strategic Opportunities Allocation Fund | MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.87%)
5 Years	rr_AverageAnnualReturnYear05	7.59%
10 Years	rr_AverageAnnualReturnYear10	4.98%
Incept.	rr_AverageAnnualReturnSinceInception	5.75%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 31, 2005
GMO Strategic Opportunities Allocation Fund | Barclays U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.55%
5 Years	rr_AverageAnnualReturnYear05	3.25%
10 Years	rr_AverageAnnualReturnYear10	4.52%
Incept.	rr_AverageAnnualReturnSinceInception	4.31%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 31, 2005
GMO Strategic Opportunities Allocation Fund | GMO Strategic Opportunities Allocation Index (Fund benchmark)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(0.33%)
5 Years	rr_AverageAnnualReturnYear05	6.67%
10 Years	rr_AverageAnnualReturnYear10	5.14%
Incept.	rr_AverageAnnualReturnSinceInception	5.65%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 31, 2005

[1] These indirect expenses include interest expense that may be incurred by certain underlying funds and also include, to the extent applicable, purchase premiums and redemption fees ("transaction fees") charged by certain underlying funds. Net fees and expenses of underlying funds (before addition of interest expense and transaction fees), indirect interest expense, and indirect transaction fees were approximately 0.49%, less than 0.01%, and 0.06%, respectively.

[2] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. This reimbursement will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[3] after expense reimbursement (Fund and underlying fund expenses)

XML

GMO Taiwan Fund

GMO TAIWAN FUND

Investment objective

Total return in excess of that of its benchmark, the MSCI Taiwan Index.

Fees and expenses

The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees	GMO Taiwan Fund Class III
Purchase premium (as a percentage of amount invested)	0.15%
Redemption fee (as a percentage of amount redeemed)	0.45%

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO Taiwan Fund Class III
Management fee	0.81%	[1]
Shareholder service fee	0.15%	[1]
Other expenses	0.37%
Acquired fund fees and expenses (underlying fund expenses)	0.01%	[2]
Total annual fund operating expenses	1.34%	[3]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you sell your shares

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO Taiwan Fund | Class III | USD ($)	198	489	802	1,690

If you do not sell your shares

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO Taiwan Fund | Class III | USD ($)	151	439	748	1,625

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 90% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 77% of the average value of its portfolio.

Principal investment strategies

The Fund typically invests directly and indirectly (e.g., through underlying funds or derivatives) in equities of companies doing business in or otherwise tied economically to Taiwan. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in investments tied economically to Taiwan (see "Name Policies").

GMO uses proprietary quantitative techniques and fundamental analysis to evaluate and select sectors and equity investments based on factors including, but not limited to, valuation and macroeconomic factors, GMO's assessment of a sector's fundamentals as well as a company's positioning relative to its competitors. In constructing the Fund's portfolio, GMO weighs a number of factors, including the trade-off among forecasted returns, risk relative to the benchmark, transaction costs, and liquidity. GMO also adjusts the Fund's portfolio for factors such as position size, market capitalization, and exposure to particular industries or sectors. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time.

The Fund may invest a significant portion of its assets in securities of issuers in industries that are subject to the same or similar risk factors or whose security prices have strong correlations (e.g., issuers in different industries within broad sectors, such as technology or financial services).

As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund's foreign currency exposure may differ from the currency exposure represented by its equity investments.

In addition, the Fund may overweight and underweight its positions in particular currencies relative to its benchmark. In addition, the Fund may lend its portfolio securities.

The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares.

• Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Certain characteristics of Taiwan’s economy and geographic location also subject the Fund to non-U.S. investment risks. For example, Taiwan is a small island with few raw material resources and limited land area and thus relies heavily on imports for its commodity needs. Any fluctuations or shortages in the commodity markets could have a negative impact on the Taiwanese economy. Also, rising labor costs and increasing environmental consciousness have led some labor-intensive industries to relocate to countries with cheaper work forces, and continued labor outsourcing may adversely affect the Taiwanese economy. Taiwan’s economy also is intricately linked with economies of Asian countries that have experienced over-extensions of credit, frequent and pronounced currency fluctuations, currency devaluations, currency repatriation, rising unemployment, and fluctuations in inflation. Currency devaluations in one country in the region can have a significant effect on all countries in the region. Political and social unrest in Asian countries could cause further economic and market uncertainty in Taiwan. In particular, the Taiwanese economy is dependent on the economies of Japan and China, as well as the United States, and a reduction in purchases by any of them of Taiwanese products and services or negative changes in their economies would likely have an adverse effect on the Taiwanese economy. Taiwan’s geographic proximity to China and Taiwan’s history of political contention with China have resulted in ongoing tensions with China, including the risk of war with China. These tensions may materially affect the Taiwanese economy and securities markets. Any of these risks, should they occur, could materially reduce the value of an investment in Taiwan Fund.

• Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies.

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

• Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices.

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

• Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated, such as the Fund’s investments tied economically to Taiwan, are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated.

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.

• Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations.

• Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

• Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

• Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests (including ETFs), including the risk that those underlying funds will not perform as expected.

• Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns/Class III Shares
Years Ending December 31

Highest Quarter: 22.85% (3Q2010)
Lowest Quarter: – 23.74% (4Q2008)
Year-to-Date (as of 3/31/16): 7.38%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO Taiwan Fund		1 Year	5 Years	10 Years	Incept.	Inception Date
Class III		(16.84%)	(2.13%)	3.08%	5.97%	Oct. 04, 2002
Class III | Return After Taxes on Distributions	[1]	(18.32%)	(2.88%)	1.79%	4.80%	Oct. 04, 2002
Class III | Return After Taxes on Distributions and Sale of Fund Shares	[1]	(8.26%)	(1.22%)	2.87%	5.23%	Oct. 04, 2002
MSCI Taiwan Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)		(11.72%)	(0.57%)	3.98%	7.77%	Oct. 04, 2002

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] These indirect expenses include commissions paid to brokers by the Fund for executing transactions in unaffiliated underlying funds ("transaction fees"). Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.01% and less than 0.01%, respectively.

[3] (Fund and underlying fund expenses)

[1] For periods prior to the public offering of the Fund's shares, which began on October 29, 2009, the Fund's after-tax returns reflect dividends that included certain non-deductible investment expenses.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO Taiwan Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO TAIWAN FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return in excess of that of its benchmark, the MSCI Taiwan Index.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may bear if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 90% of the average value of its portfolio. That portfolio turnover rate includes investments in U.S. Treasury Fund, which the Fund uses as a short-term investment vehicle for cash management. The Fund’s portfolio turnover rate during its fiscal year ended February 29, 2016, excluding transactions in U.S. Treasury Fund, was 77% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	90.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If you do not sell your shares
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund typically invests directly and indirectly (e.g., through underlying funds or derivatives) in equities of companies doing business in or otherwise tied economically to Taiwan. The term "equities" refers to direct and indirect investments in common and preferred stocks and other stock-related securities, such as convertible securities, depositary receipts, and equity real estate investment trusts (REITs) and income trusts. Under normal circumstances, the Fund invests directly and indirectly at least 80% of its assets in investments tied economically to Taiwan (see "Name Policies"). GMO uses proprietary quantitative techniques and fundamental analysis to evaluate and select sectors and equity investments based on factors including, but not limited to, valuation and macroeconomic factors, GMO's assessment of a sector's fundamentals as well as a company's positioning relative to its competitors. In constructing the Fund's portfolio, GMO weighs a number of factors, including the trade-off among forecasted returns, risk relative to the benchmark, transaction costs, and liquidity. GMO also adjusts the Fund's portfolio for factors such as position size, market capitalization, and exposure to particular industries or sectors. The Fund may invest in securities of companies of any market capitalization. The factors GMO considers and investment methods GMO uses can change over time. The Fund may invest a significant portion of its assets in securities of issuers in industries that are subject to the same or similar risk factors or whose security prices have strong correlations (e.g., issuers in different industries within broad sectors, such as technology or financial services). As an alternative to investing directly in equities, the Fund may invest in exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (ETFs). The Fund also may invest in derivatives and ETFs in an attempt to obtain or adjust elements of its long or short investment exposure, and as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund's foreign currency exposure may differ from the currency exposure represented by its equity investments. In addition, the Fund may overweight and underweight its positions in particular currencies relative to its benchmark. In addition, the Fund may lend its portfolio securities. The Fund also may invest in U.S. Treasury Fund, in money market funds unaffiliated with GMO, or directly in the types of investments typically held by money market funds.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer, its industry or the economy and equity markets generally. If the Fund purchases an equity for less than its fundamental fair (or intrinsic) value as determined by GMO, the Fund runs the risk that the market price of the equity will not appreciate or will decline due to GMO’s incorrect assessment of the equity’s fundamental fair (or intrinsic) value. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these equities often are more sensitive to changes in future earnings expectations than the market prices of equities trading at lower multiples. Declines in stock market prices generally are likely to reduce the net asset value of the Fund’s shares. Non-U.S. Investment Risk – The market prices of many non-U.S. securities fluctuate more than those of U.S. securities. Many non-U.S. securities markets are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the cost of trading in those markets often is higher than in U.S. securities markets. Transactions in non-U.S. securities generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in U.S. securities. In addition, the Fund may be subject to non-U.S. taxes, including potentially on a retroactive basis, on (i) capital gains it realizes or dividends, interest, or other amounts it realizes or accrues in respect of non-U.S. investments; (ii) transactions in those investments; and (iii) repatriation of proceeds generated from the sale or other disposition of those investments. Also, the Fund needs a license to invest directly in many non-U.S. securities markets, and the Fund is subject to the risk that it could not invest if its license were terminated or suspended. In some non-U.S. securities markets, prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks. Further, adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. These and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers) tend to be greater for investments in companies tied economically to emerging countries, the economies of which may be predominantly based on only a few industries or dependent on revenues from particular commodities and which often are more volatile than the economies of developed countries. Certain characteristics of Taiwan’s economy and geographic location also subject the Fund to non-U.S. investment risks. For example, Taiwan is a small island with few raw material resources and limited land area and thus relies heavily on imports for its commodity needs. Any fluctuations or shortages in the commodity markets could have a negative impact on the Taiwanese economy. Also, rising labor costs and increasing environmental consciousness have led some labor-intensive industries to relocate to countries with cheaper work forces, and continued labor outsourcing may adversely affect the Taiwanese economy. Taiwan’s economy also is intricately linked with economies of Asian countries that have experienced over-extensions of credit, frequent and pronounced currency fluctuations, currency devaluations, currency repatriation, rising unemployment, and fluctuations in inflation. Currency devaluations in one country in the region can have a significant effect on all countries in the region. Political and social unrest in Asian countries could cause further economic and market uncertainty in Taiwan. In particular, the Taiwanese economy is dependent on the economies of Japan and China, as well as the United States, and a reduction in purchases by any of them of Taiwanese products and services or negative changes in their economies would likely have an adverse effect on the Taiwanese economy. Taiwan’s geographic proximity to China and Taiwan’s history of political contention with China have resulted in ongoing tensions with China, including the risk of war with China. These tensions may materially affect the Taiwanese economy and securities markets. Any of these risks, should they occur, could materially reduce the value of an investment in Taiwan Fund. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s foreign currency holdings and investments denominated in foreign currencies. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO often uses quantitative models as part of its investment process. GMO’s models are not necessarily predictive of future market events and use simplifying assumptions that can limit their effectiveness. In addition, the data on which the models are based is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect the Fund’s performance. The Fund also runs the risk that GMO’s assessment of an investment (including a company’s fundamental fair (or intrinsic) value) may be wrong or that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions may limit or prevent the Fund from selling particular securities or closing derivative positions at desirable prices. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments. Focused Investment Risk – Investments focused in countries, regions, sectors, industries, or issuers that are subject to the same or similar risk factors and investments whose prices are closely correlated, such as the Fund’s investments tied economically to Taiwan, are subject to greater overall risk than investments that are more diversified or whose prices are not as closely correlated. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Small Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, may have inexperienced managers or may depend on a few key employees. The securities of companies with smaller market capitalizations often are less widely held and trade less frequently and in lesser quantities, and their market prices often fluctuate more, than the securities of companies with larger market capitalizations. Counterparty Risk – The Fund runs the risk that the counterparty to a derivatives contract, a clearing member used by the Fund to hold a cleared derivatives contract, or a borrower of the Fund’s securities will be unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations. Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, illiquidity risk, currency risk, credit risk, and counterparty risk. The market price of an option is affected by many factors, including changes in the market prices or dividend rates of underlying securities (or in the case of indices, the securities in such indices); the time remaining before expiration; changes in interest rates or exchange rates; and changes in the actual or perceived volatility of the relevant stock market and underlying securities. The Fund may create short investment exposure by taking a derivative position in which the value of the derivative moves in the opposite direction from the price of an underlying investment, pool of investments, index or currency. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited. Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests (including ETFs), including the risk that those underlying funds will not perform as expected. Leveraging Risk – The use of reverse repurchase agreements and other derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 22.85% (3Q2010) Lowest Quarter: – 23.74% (4Q2008) Year-to-Date (as of 3/31/16): 7.38%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO Taiwan Fund | Class III
Risk/Return:	rr_RiskReturnAbstract
Purchase premium (as a percentage of amount invested)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	0.15%
Redemption fee (as a percentage of amount redeemed)	rr_RedemptionFeeOverRedemption	0.45%
Management fee	rr_ManagementFeesOverAssets	0.81%	[1]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.15%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.37%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.34%	[3]
1 Year	rr_ExpenseExampleYear01	$ 198
3 Years	rr_ExpenseExampleYear03	489
5 Years	rr_ExpenseExampleYear05	802
10 Years	rr_ExpenseExampleYear10	1,690
1 Year	rr_ExpenseExampleNoRedemptionYear01	151
3 Years	rr_ExpenseExampleNoRedemptionYear03	439
5 Years	rr_ExpenseExampleNoRedemptionYear05	748
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,625
2006	rr_AnnualReturn2006	20.41%
2007	rr_AnnualReturn2007	3.95%
2008	rr_AnnualReturn2008	(44.22%)
2009	rr_AnnualReturn2009	73.06%
2010	rr_AnnualReturn2010	24.84%
2011	rr_AnnualReturn2011	(13.45%)
2012	rr_AnnualReturn2012	11.62%
2013	rr_AnnualReturn2013	6.17%
2014	rr_AnnualReturn2014	5.30%
2015	rr_AnnualReturn2015	(16.34%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	7.38%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2010
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	22.85%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(23.74%)
1 Year	rr_AverageAnnualReturnYear01	(16.84%)
5 Years	rr_AverageAnnualReturnYear05	(2.13%)
10 Years	rr_AverageAnnualReturnYear10	3.08%
Incept.	rr_AverageAnnualReturnSinceInception	5.97%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 04, 2002
GMO Taiwan Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(18.32%)	[4]
5 Years	rr_AverageAnnualReturnYear05	(2.88%)	[4]
10 Years	rr_AverageAnnualReturnYear10	1.79%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	4.80%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 04, 2002	[4]
GMO Taiwan Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(8.26%)	[4]
5 Years	rr_AverageAnnualReturnYear05	(1.22%)	[4]
10 Years	rr_AverageAnnualReturnYear10	2.87%	[4]
Incept.	rr_AverageAnnualReturnSinceInception	5.23%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 04, 2002	[4]
GMO Taiwan Fund | MSCI Taiwan Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(11.72%)
5 Years	rr_AverageAnnualReturnYear05	(0.57%)
10 Years	rr_AverageAnnualReturnYear10	3.98%
Incept.	rr_AverageAnnualReturnSinceInception	7.77%
Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 04, 2002

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] These indirect expenses include commissions paid to brokers by the Fund for executing transactions in unaffiliated underlying funds ("transaction fees"). Net fees and expenses of underlying funds (before addition of transaction fees) and indirect transaction fees were approximately 0.01% and less than 0.01%, respectively.

[3] (Fund and underlying fund expenses)

[4] For periods prior to the public offering of the Fund's shares, which began on October 29, 2009, the Fund's after-tax returns reflect dividends that included certain non-deductible investment expenses.

XML

GMO U.S. Treasury Fund

GMO U.S. TREASURY FUND

Investment objective

Liquidity and safety of principal

with current income as a secondary objective.

Fees and expenses

The table below describes the fees and expenses that you may bear if you buy and hold shares of the Fund.

Annual Fund operating expenses
(expenses that you bear each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	GMO U.S. Treasury Fund GMO U.S. Treasury Fund
Management fee	0.08%	[1]
Other expenses	0.02%
Total annual fund operating expenses	0.10%
Expense reimbursement/waiver	(0.02%)	[1]
Total annual fund operating expenses	0.08%	[2]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amount shown reflects the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
GMO U.S. Treasury Fund | GMO U.S. Treasury Fund | USD ($)	8	30	54	126

Expense Example, No Redemption	1 Year	3 Years	5 Years	10 Years
GMO U.S. Treasury Fund | GMO U.S. Treasury Fund | USD ($)	8	30	54	126

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 0% of the average value of its portfolio.

Principal investment strategies

GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other funds or accounts managed by GMO. Accordingly, the Fund is not a standalone investment.

Under normal circumstances, the Fund invests at least 80% of its assets in Direct U.S. Treasury Obligations and repurchase agreements collateralized by these Obligations (see "Name Policies"). "Direct U.S. Treasury Obligations" include U.S. Treasury bills, bonds and notes and other securities issued by the U.S. Treasury, as well as Separately Traded Registered Interest and Principal Securities (STRIPS) and other zero-coupon securities. GMO normally seeks to maintain an interest rate duration of one year or less for the Fund's portfolio. For an additional discussion of duration, see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Bond Funds — Duration."

The Fund also may enter into repurchase agreements, under which the Fund purchases a security backed by the full faith and credit of the U.S. government from a seller who simultaneously commits to repurchase, on an agreed upon date in the future, the security from the Fund at the original purchase price plus an agreed upon amount representing the original purchase price plus interest. The counterparties in repurchase agreements are typically brokers and banks, and the safety of the arrangement depends on, among other things, the Fund's having an interest in the security that it can realize in the event of the insolvency of the counterparty.

In addition to Direct U.S. Treasury Obligations, the Fund may invest in other fixed income securities that are backed by the full faith and credit of the U.S. government, such as fixed income securities issued by the Government National Mortgage Association (GNMA) and the Federal Deposit Insurance Corporation (FDIC) that are guaranteed by the U.S. government. The Fund also may invest in money market funds unaffiliated with GMO.

Although the fixed income securities purchased by the Fund normally will have a stated or remaining maturity of one year or less, Direct U.S. Treasury Obligations purchased pursuant to repurchase agreements may not, and, therefore, if the counterparty to the repurchase agreement defaults, the Fund may end up owning a security with a stated or remaining maturity of more than one year.

The Fund is not a money market fund and is not subject to the duration, quality, diversification and other requirements applicable to money market funds.

In selecting U.S. Treasury securities for the Fund's portfolio, GMO focuses primarily on the relative attractiveness of different obligations (such as bonds, notes or bills), which can vary depending on the general level of interest rates as well as supply and demand imbalances and other market conditions. The factors GMO considers and investment methods GMO uses can change over time.

Principal risks of investing in the Fund

The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.”

• Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, primarily rising interest rates.
  

• Credit Risk – Securities issued by the U.S. Treasury historically have presented minimal credit risk. However, events in 2011 led to a downgrade in the long-term credit rating of U.S. bonds by several major rating agencies and introduced greater uncertainty about the repayment by the United States of its obligations. A further credit rating downgrade could decrease, and a U.S. credit default would decrease, the value of the Fund’s investments and increase the volatility of the Fund’s portfolio.

• Focused Investment Risk – Because the Fund’s investments are focused in investments in securities issued by the U.S. Treasury and other fixed income securities that are backed by the full faith and credit of the U.S. government, the Fund is subject to greater U.S. Treasury credit risk than a more diversified Fund.
  

• Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations.
  

• Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. The Fund also runs the risk that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.
  

• Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.

Annual Total Returns
Years Ending December 31

Highest Quarter: 0.07% (2Q2010)
Lowest Quarter: – 0.02% (4Q2011)
Year-to-Date (as of 3/31/16): 0.17%

Average Annual Total Returns
Periods Ending December 31, 2015

Average Annual Total Returns - GMO U.S. Treasury Fund	1 Year	5 Years	10 Years	Incept.	Inception Date
GMO U.S. Treasury Fund	0.11%	0.09%		0.12%	Mar. 17, 2009
GMO U.S. Treasury Fund | Return After Taxes on Distributions	0.04%	0.05%		0.07%	Mar. 17, 2009
GMO U.S. Treasury Fund | Return After Taxes on Distributions and Sale of Fund Shares	0.06%	0.05%		0.08%	Mar. 17, 2009
Citigroup 3-Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes)	0.03%	0.05%		0.08%	Mar. 17, 2009

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees to the extent necessary to offset the management fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
GMO U.S. Treasury Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO U.S. TREASURY FUND
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Liquidity and safety of principal
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	with current income as a secondary objective.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may bear if you buy and hold shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2017
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities. A higher portfolio turnover rate may result in higher transaction costs and, when Fund shares are held in a taxable account, higher taxes. These transaction costs, which are not reflected in Annual Fund operating expenses or in the Example, affect the Fund’s performance. During its fiscal year ended February 29, 2016, the Fund’s portfolio turnover rate (excluding short-term investments) was 0% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	none
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amount shown reflects the expense reimbursement and waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	GMO pursues investment strategies for the Fund that are intended to complement the strategies it is pursuing in other funds or accounts managed by GMO. Accordingly, the Fund is not a standalone investment. Under normal circumstances, the Fund invests at least 80% of its assets in Direct U.S. Treasury Obligations and repurchase agreements collateralized by these Obligations (see "Name Policies"). "Direct U.S. Treasury Obligations" include U.S. Treasury bills, bonds and notes and other securities issued by the U.S. Treasury, as well as Separately Traded Registered Interest and Principal Securities (STRIPS) and other zero-coupon securities. GMO normally seeks to maintain an interest rate duration of one year or less for the Fund's portfolio. For an additional discussion of duration, see "Additional Information About the Funds' Investment Strategies, Risks, and Expenses — Bond Funds — Duration." The Fund also may enter into repurchase agreements, under which the Fund purchases a security backed by the full faith and credit of the U.S. government from a seller who simultaneously commits to repurchase, on an agreed upon date in the future, the security from the Fund at the original purchase price plus an agreed upon amount representing the original purchase price plus interest. The counterparties in repurchase agreements are typically brokers and banks, and the safety of the arrangement depends on, among other things, the Fund's having an interest in the security that it can realize in the event of the insolvency of the counterparty. In addition to Direct U.S. Treasury Obligations, the Fund may invest in other fixed income securities that are backed by the full faith and credit of the U.S. government, such as fixed income securities issued by the Government National Mortgage Association (GNMA) and the Federal Deposit Insurance Corporation (FDIC) that are guaranteed by the U.S. government. The Fund also may invest in money market funds unaffiliated with GMO. Although the fixed income securities purchased by the Fund normally will have a stated or remaining maturity of one year or less, Direct U.S. Treasury Obligations purchased pursuant to repurchase agreements may not, and, therefore, if the counterparty to the repurchase agreement defaults, the Fund may end up owning a security with a stated or remaining maturity of more than one year. The Fund is not a money market fund and is not subject to the duration, quality, diversification and other requirements applicable to money market funds. In selecting U.S. Treasury securities for the Fund's portfolio, GMO focuses primarily on the relative attractiveness of different obligations (such as bonds, notes or bills), which can vary depending on the general level of interest rates as well as supply and demand imbalances and other market conditions. The factors GMO considers and investment methods GMO uses can change over time.
Risk [Heading]	rr_RiskHeading	Principal risks of investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Description of Principal Risks.” Market Risk – Fixed Income Investments – The market price of a fixed income investment can decline due to market-related factors, primarily rising interest rates. Credit Risk – Securities issued by the U.S. Treasury historically have presented minimal credit risk. However, events in 2011 led to a downgrade in the long-term credit rating of U.S. bonds by several major rating agencies and introduced greater uncertainty about the repayment by the United States of its obligations. A further credit rating downgrade could decrease, and a U.S. credit default would decrease, the value of the Fund’s investments and increase the volatility of the Fund’s portfolio. Focused Investment Risk – Because the Fund’s investments are focused in investments in securities issued by the U.S. Treasury and other fixed income securities that are backed by the full faith and credit of the U.S. government, the Fund is subject to greater U.S. Treasury credit risk than a more diversified Fund. Large Shareholder Risk – To the extent that a large number of shares of the Fund is held by a single shareholder (e.g., an institutional investor or another GMO Fund) or a group of shareholders with a common investment strategy (e.g., GMO asset allocation accounts), the Fund is subject to the risk that a redemption by those shareholders of all or a large portion of their Fund shares will require the Fund to sell securities at disadvantageous prices or otherwise disrupt the Fund’s operations. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. The Fund also runs the risk that deficiencies in GMO’s or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations. Market Disruption and Geopolitical Risk – Geopolitical and other events may disrupt securities markets and adversely affect global economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could adversely affect the value of the Fund’s investments.
Risk Lose Money [Text]	rr_RiskLoseMoney	Many factors can affect this value, and you may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of a broad-based index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.gmo.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns Years Ending December 31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter: 0.07% (2Q2010) Lowest Quarter: – 0.02% (4Q2011) Year-to-Date (as of 3/31/16): 0.17%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2015
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
GMO U.S. Treasury Fund | GMO U.S. Treasury Fund
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.08%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.02%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.10%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total annual fund operating expenses	rr_NetExpensesOverAssets	0.08%	[2]
1 Year	rr_ExpenseExampleYear01	$ 8
3 Years	rr_ExpenseExampleYear03	30
5 Years	rr_ExpenseExampleYear05	54
10 Years	rr_ExpenseExampleYear10	126
1 Year	rr_ExpenseExampleNoRedemptionYear01	8
3 Years	rr_ExpenseExampleNoRedemptionYear03	30
5 Years	rr_ExpenseExampleNoRedemptionYear05	54
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 126
2010	rr_AnnualReturn2010	0.10%
2011	rr_AnnualReturn2011	0.09%
2012	rr_AnnualReturn2012	0.10%
2013	rr_AnnualReturn2013	0.11%
2014	rr_AnnualReturn2014	0.06%
2015	rr_AnnualReturn2015	0.11%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.17%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2010
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	0.07%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(0.02%)
1 Year	rr_AverageAnnualReturnYear01	0.11%
5 Years	rr_AverageAnnualReturnYear05	0.09%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 17, 2009
GMO U.S. Treasury Fund | Return After Taxes on Distributions | GMO U.S. Treasury Fund
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.04%
5 Years	rr_AverageAnnualReturnYear05	0.05%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.07%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 17, 2009
GMO U.S. Treasury Fund | Return After Taxes on Distributions and Sale of Fund Shares | GMO U.S. Treasury Fund
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.06%
5 Years	rr_AverageAnnualReturnYear05	0.05%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.08%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 17, 2009
GMO U.S. Treasury Fund | Citigroup 3-Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.03%
5 Years	rr_AverageAnnualReturnYear05	0.05%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.08%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 17, 2009

[1] Grantham, Mayo, Van Otterloo & Co. LLC ("GMO") has contractually agreed to reimburse the Fund for the following expenses: audit expenses, fund accounting expenses, pricing service expenses, expenses of non-investment related tax services, transfer agency expenses, expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund's management fees to the extent necessary to offset the management fees paid to GMO that are directly or indirectly borne by the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees will not be waived below zero. This reimbursement and waiver will continue through at least June 30, 2017, and may not be terminated prior to this date without the action or consent of the Fund's Board of Trustees.

[2] after expense reimbursement/waiver

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2016
Document Creation Date	dei_DocumentCreationDate	Jun. 30, 2016