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.