Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2013
GMO Trust | 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.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The tables below describe the fees and expenses that you may pay 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 pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	June 30, 2014
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 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 28, 2013, the Fund’s portfolio turnover rate (excluding short-term investments) was 119% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	119.00%
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 makes equity investments directly and indirectly (e.g., through underlying funds or derivatives) in 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 “equity investments” refers to direct and indirect investments in common stocks and other stock-related securities, such as preferred stocks, convertible securities, depositary receipts, and exchange-traded 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 the Manager believes are likely to benefit from growth in the emerging markets. The Manager expects that the Fund will have a value bias relative to its benchmark. The Manager 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 patterns of price movement or price volatility. The Manager also adjusts the Fund’s portfolio for factors such as position size, market capitalization, and exposure to factors such as industry, sector, country, or currency. The factors considered and investment methods used by the Manager can change over time. As a substitute for direct investments in equities, the Fund may use exchange-traded and over-the-counter (OTC) derivatives and exchange-traded funds (“ETFs”). The Fund also may use derivatives and ETFs: (i) in an attempt to reduce investment exposures (which may result in a reduction below zero); (ii) in an attempt to adjust elements of the Fund’s investment exposure; and (iii) as a substitute for securities lending. Derivatives used may include options, futures, warrants, swap contracts, and reverse repurchase agreements. The Fund’s non-U.S. currency exposure may differ from the currency exposure represented by its equity investments. In addition, the Fund may take active overweighted and underweighted 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 and money market funds that are unaffiliated with GMO.
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 prices of equities may decline due to factors affecting the issuing companies, their industries, or the economy and equity markets generally. If the Fund purchases equities at a discount from their value as determined by the Manager, the Fund runs the risk that the market prices of these investments will not appreciate or will decline for a variety of reasons, one of which may be the Manager’s overestimation of the value of those investments. The Fund also may purchase equities that typically trade at higher multiples of current earnings than other securities, and the market prices of these investments 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. markets are less stable, smaller, less liquid, and less regulated than U.S. markets, and the cost of trading in those markets often is higher than in U.S. markets. Non-U.S. portfolio transactions generally involve higher commission rates, transfer taxes, and custodial costs than similar transactions in the U.S. 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 or interest it receives on non-U.S. investments, (ii) transactions in those investments, and (iii) the repatriation of proceeds generated from the sale of those investments. Also, many non-U.S. markets require a license for the Fund to invest directly in those 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. 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 with respect to participating brokers, custodians, clearing banks or other clearing agents, escrow agents and issuers. 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 markets, the economies of which tend to be more volatile than the economies of developed markets. Currency Risk – Fluctuations in exchange rates can adversely affect the market value of the Fund’s non-U.S. currency holdings and investments denominated in non-U.S. currencies. Liquidity 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 unwinding derivative positions at desirable prices. In addition, the Fund may buy securities that are less liquid than those in its benchmark. 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. Smaller Company Risk – Smaller companies may have limited product lines, markets, or financial resources, may lack the competitive strength of larger companies, or may lack managers with experience or depend on a few key employees. The securities of small- and mid-cap companies 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. The Fund may buy securities that have smaller market capitalizations than those in its benchmark. Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. The Fund’s portfolio managers may use quantitative analyses and models, and any imperfections, errors, or limitations in those analyses and models could affect the ability of the portfolio managers to implement the Fund’s strategies. By necessity, these analyses and models make simplifying assumptions that limit their efficacy. Models that appear to explain prior market data can fail to predict future market events. Further, the data used in models may be inaccurate and may not include the most recent information about a company or a security. The Fund also runs the risk that GMO’s assessment of an investment 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 – Focusing investments in a limited number of countries and geographic regions creates more risk than if the Fund’s investments were less correlated. Derivatives Risk – The use of derivatives involves the risk that their value may not move as expected relative to the value of the underlying assets, rates, or indices. Derivatives also present other risks, including market risk, liquidity risk, currency risk, and counterparty risk. 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 (including ETFs) 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 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-deferred 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. 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: 31.90% (2Q2009) Lowest Quarter: – 30.50% (4Q2008) Year-to-Date (as of 3/31/13): – 2.79%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns Periods Ending December 31, 2012
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-deferred 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 Trust | 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	0.12%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[3]
Total annual operating expenses	rr_ExpensesOverAssets	1.11%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.03%)	[2]
Total annual operating expenses after expense reimbursement/waiver	rr_NetExpensesOverAssets	1.08%
1 Year	rr_ExpenseExampleYear01	$ 272	[4]
3 Years	rr_ExpenseExampleYear03	516
5 Years	rr_ExpenseExampleYear05	780
10 Years	rr_ExpenseExampleYear10	1,534
1 Year	rr_ExpenseExampleNoRedemptionYear01	189	[4]
3 Years	rr_ExpenseExampleNoRedemptionYear03	427
5 Years	rr_ExpenseExampleNoRedemptionYear05	684
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,418
1 Year	rr_AverageAnnualReturnYear01	14.37%	[5]
5 Years	rr_AverageAnnualReturnYear05	(2.69%)	[5]
10 Years	rr_AverageAnnualReturnYear10	16.57%	[5]
Incept.	rr_AverageAnnualReturnSinceInception	10.00%	[5]
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 29, 1996	[5]
GMO Trust | 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	0.12%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[3]
Total annual operating expenses	rr_ExpensesOverAssets	1.04%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual operating expenses after expense reimbursement/waiver	rr_NetExpensesOverAssets	1.03%
1 Year	rr_ExpenseExampleYear01	267	[4]
3 Years	rr_ExpenseExampleYear03	496
5 Years	rr_ExpenseExampleYear05	745
10 Years	rr_ExpenseExampleYear10	1,457
1 Year	rr_ExpenseExampleNoRedemptionYear01	184	[4]
3 Years	rr_ExpenseExampleNoRedemptionYear03	407
5 Years	rr_ExpenseExampleNoRedemptionYear05	648
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,340
2003	rr_AnnualReturn2003	70.13%
2004	rr_AnnualReturn2004	26.59%
2005	rr_AnnualReturn2005	39.71%
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%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-Date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(2.79%)
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	14.36%
5 Years	rr_AverageAnnualReturnYear05	(2.64%)
10 Years	rr_AverageAnnualReturnYear10	16.65%
Incept.	rr_AverageAnnualReturnSinceInception	9.22%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 09, 1993
GMO Trust | 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	0.12%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[3]
Total annual operating expenses	rr_ExpensesOverAssets	1.00%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[2]
Total annual operating expenses after expense reimbursement/waiver	rr_NetExpensesOverAssets	0.99%
1 Year	rr_ExpenseExampleYear01	263	[4]
3 Years	rr_ExpenseExampleYear03	484
5 Years	rr_ExpenseExampleYear05	724
10 Years	rr_ExpenseExampleYear10	1,411
1 Year	rr_ExpenseExampleNoRedemptionYear01	180	[4]
3 Years	rr_ExpenseExampleNoRedemptionYear03	395
5 Years	rr_ExpenseExampleNoRedemptionYear05	627
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,294
1 Year	rr_AverageAnnualReturnYear01	14.47%
5 Years	rr_AverageAnnualReturnYear05	(2.58%)
10 Years	rr_AverageAnnualReturnYear10	16.71%
Incept.	rr_AverageAnnualReturnSinceInception	11.69%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998
GMO Trust | 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%
Management fee	rr_ManagementFeesOverAssets	0.75%	[2]
Shareholder service fee	rr_DistributionOrSimilarNon12b1FeesOverAssets	0.085%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.12%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[3]
Total annual operating expenses	rr_ExpensesOverAssets	0.98%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[2]
Total annual operating expenses after expense reimbursement/waiver	rr_NetExpensesOverAssets	0.94%
1 Year	rr_ExpenseExampleYear01	258	[4]
3 Years	rr_ExpenseExampleYear03	475
5 Years	rr_ExpenseExampleYear05	710
10 Years	rr_ExpenseExampleYear10	1,386
1 Year	rr_ExpenseExampleNoRedemptionYear01	175	[4]
3 Years	rr_ExpenseExampleNoRedemptionYear03	386
5 Years	rr_ExpenseExampleNoRedemptionYear05	613
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,268
1 Year	rr_AverageAnnualReturnYear01	14.55%	[6]
5 Years	rr_AverageAnnualReturnYear05	(2.54%)	[6]
10 Years	rr_AverageAnnualReturnYear10		[6]
Incept.	rr_AverageAnnualReturnSinceInception	15.28%	[6]
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 04, 2003	[6]
GMO Trust | 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	0.12%
Acquired fund fees and expenses (underlying fund expenses)	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[3]
Total annual operating expenses	rr_ExpensesOverAssets	0.95%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[2]
Total annual operating expenses after expense reimbursement/waiver	rr_NetExpensesOverAssets	0.91%
1 Year	rr_ExpenseExampleYear01	255	[4]
3 Years	rr_ExpenseExampleYear03	466
5 Years	rr_ExpenseExampleYear05	694
10 Years	rr_ExpenseExampleYear10	1,352
1 Year	rr_ExpenseExampleNoRedemptionYear01	172	[4]
3 Years	rr_ExpenseExampleNoRedemptionYear03	376
5 Years	rr_ExpenseExampleNoRedemptionYear05	597
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,233
1 Year	rr_AverageAnnualReturnYear01	14.56%
5 Years	rr_AverageAnnualReturnYear05	(2.52%)
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	15.65%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 30, 2003
GMO Trust | GMO Emerging Markets Fund | Return After Taxes on Distributions | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	14.25%
5 Years	rr_AverageAnnualReturnYear05	(3.83%)
10 Years	rr_AverageAnnualReturnYear10	14.49%
Incept.	rr_AverageAnnualReturnSinceInception	7.68%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 09, 1993
GMO Trust | GMO Emerging Markets Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	10.02%
5 Years	rr_AverageAnnualReturnYear05	(2.24%)
10 Years	rr_AverageAnnualReturnYear10	14.74%
Incept.	rr_AverageAnnualReturnSinceInception	7.83%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 09, 1993
GMO Trust | GMO Emerging Markets Fund | S&P/IFCI Composite (reflects no deduction for fees, expenses, or taxes) | Class II
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	18.89%	[5]
5 Years	rr_AverageAnnualReturnYear05	(0.56%)	[5]
10 Years	rr_AverageAnnualReturnYear10	17.50%	[5]
Incept.	rr_AverageAnnualReturnSinceInception	8.54%	[5]
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 29, 1996	[5]
GMO Trust | GMO Emerging Markets Fund | S&P/IFCI Composite (reflects no deduction for fees, expenses, or taxes) | Class III
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	18.89%
5 Years	rr_AverageAnnualReturnYear05	(0.56%)
10 Years	rr_AverageAnnualReturnYear10	17.50%
Incept.	rr_AverageAnnualReturnSinceInception	7.02%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 09, 1993
GMO Trust | GMO Emerging Markets Fund | S&P/IFCI Composite (reflects no deduction for fees, expenses, or taxes) | Class IV
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	18.89%
5 Years	rr_AverageAnnualReturnYear05	(0.56%)
10 Years	rr_AverageAnnualReturnYear10	17.50%
Incept.	rr_AverageAnnualReturnSinceInception	11.13%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 09, 1998
GMO Trust | GMO Emerging Markets Fund | S&P/IFCI Composite (reflects no deduction for fees, expenses, or taxes) | Class V
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	18.89%	[6]
5 Years	rr_AverageAnnualReturnYear05	(0.56%)	[6]
10 Years	rr_AverageAnnualReturnYear10		[6]
Incept.	rr_AverageAnnualReturnSinceInception	16.07%	[6]
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 04, 2003	[6]
GMO Trust | GMO Emerging Markets Fund | S&P/IFCI Composite (reflects no deduction for fees, expenses, or taxes) | Class VI
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	18.89%
5 Years	rr_AverageAnnualReturnYear05	(0.56%)
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	16.55%
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 (the "Manager" or "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 the Manager, federal securities law filing expenses, printing expenses and state and federal registration fees. The Manager also has 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 directly or indirectly paid to the Manager as a result of the Fund's direct or indirect investments in other GMO Funds. Management fees and shareholder service fees will not be waived below zero. In addition, the Manager has 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, 2014, 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 broker-dealers 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 reimbursement

[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 operating expenses (Class II's expenses during these periods were calculated by adjusting Class III's actual total annual operating expenses during such periods upward by the current differential between "Total annual 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.