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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 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 Jun. 30, 2021
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, for holders of Fund shares subject to U.S. taxes, higher income 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, 2020, 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, 2020, excluding transactions in U.S. Treasury Fund and other short-term investments, was 37% 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, 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 the Fund’s assets primarily in equities of companies in the natural resources sector (as defined below). Given the expected growth and industrialization of emerging countries, GMO believes that global demand for many natural resources will increase and, given the limited supply of many natural resources, that prices of these natural resources 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, and avoid companies it believes will be adversely affected by, this expected long-term increase in natural resource prices. GMO expects the Fund’s long-term performance to have a low correlation to the performance of equity markets.

GMO selects the securities the Fund buys and sells based on its evaluation of companies’ published financial information and corporate behavior (such as profit warnings, share issuance or repurchase, and director dealings in company stock), sustainability and other ESG (environmental, social, and governance) criteria, 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 GMO believes have positive return potential relative to other securities of companies in the natural resources sector. Some of these methods evaluate individual companies or groups of companies based on the ratio of their security price to historical financial information and forecasted financial information, such as profitability, cash flow and earnings, and a comparison of these ratios to current and historical industry, market or company averages. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to other securities in the natural resources sector. At times, the Fund may have substantial exposure to a single asset class, industry, sector, country, region or issuer. The Fund may invest its assets in securities of companies of any market capitalization and may invest significantly in securities of issuers with smaller market capitalizations. The Fund also may engage in merger arbitrage. 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 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, and 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 “Additional Information about the Funds’ Investment Strategies, Risks, and Expenses” and “Description of Principal Risks.”

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Focused Investment Risk – Because the Fund concentrates its investments in the natural resources sector, it is particularly exposed to adverse developments, including adverse price movements, affecting issuers in the natural resources 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 (particularly in the short term) than those of 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 the supplies they purchase and the products they sell, which can affect their profitability, and are often capital-intensive and use significant amounts of leverage. Projects in the natural resources sector may take extended periods of time to complete, 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, companies in the natural resources sector can be especially affected by political and economic developments, government regulations including changes in tax law or interpretations of law, energy conservation, and the success of exploration projects. Specifically, companies in the natural resources sector can be significantly affected by import controls, worldwide competition and cartels, and changes in consumer sentiment and spending and can be subject to liability for, among other things, environmental damage, depletion of resources, and mandated expenditures for safety and pollution control. The Fund’s concentration in the securities of natural resource companies exposes it to the price movements of natural resources to a greater extent than if it were more broadly diversified. 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.

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

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Market Risk – Equities – The market price of an equity may decline due to factors affecting the issuer or 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 assessed 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. 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.

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Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce desired results. GMO uses quantitative models as part of its investment process. GMO’s models may not accurately predict future market movements or characteristics. In addition, they are based on assumptions that can limit their effectiveness, and they rely on data that is subject to limitations (e.g., inaccuracies, staleness) that could adversely affect their predictive value. The Fund also runs the risk that GMO’s assessment of an investment (including a security’s fundamental fair (or intrinsic) value) is 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.

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Smaller Company Risk – Smaller companies may have limited product lines, markets, or financial resources, lack the competitive strength of larger companies, have inexperienced managers or 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 (particularly of companies tied economically to emerging countries) fluctuate more than those of U.S. securities. Many non-U.S. securities markets (particularly emerging 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. In addition, issuers of non-U.S. securities (particularly those tied economically to emerging countries) often are not subject to as much regulation as U.S. issuers, and the reporting, accounting, custody, and auditing standards to which those issuers are subject often are not as rigorous as U.S. standards. 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, 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 securities traded 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, difficulties in obtaining and enforcing legal judgments) tend to be greater for investments in the securities of companies tied economically to emerging countries. The economies of emerging countries may be predominantly based on only a few industries or dependent on revenues from particular commodities, and often are more volatile than the economies of developed countries.

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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.

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Market Disruption and Geopolitical Risk – Geopolitical and other events (e.g., wars, pandemics, terrorism) 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.

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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.

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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, pools of assets, rates, currencies 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 asset, pool of assets, rate, currency or index. The risks of loss associated with derivatives that provide short investment exposure and short sales of securities are theoretically unlimited.

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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 is unable or unwilling to make timely settlement payments, return the Fund’s margin or otherwise honor its obligations.

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Leveraging Risk – The use of derivatives and securities lending creates leverage. Leverage increases the Fund’s losses when the value of its investments (including derivatives) declines. In addition, the Fund’s portfolio will be leveraged if it exercises its right to delay payment on a redemption, and losses will result if the value of the Fund’s assets declines between the time a redemption request is deemed to be received by the Fund and the time the Fund liquidates assets to meet that request.

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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 price of the securities purchased by the Fund is likely to decline sharply, resulting in losses to the Fund. The risk/reward payout of merger arbitrage strategies typically is asymmetric, with the losses in failed transactions often far exceeding 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. As of the date of this Prospectus, there are no Class R6 shares or Class I shares outstanding or such shares have not been outstanding for a full calendar year. The returns information below is for the Fund’s Class III shares. Class R6 and Class I shares would have substantially similar annual returns to Class III shares because they invest in the same portfolio of securities. Their annual returns would differ from Class III shares to the extent that they bear different expenses. While Class R6 shares are expected to bear the same expenses as Class III shares, Class I shares bear higher expenses than Class III shares and therefore would have lower returns. 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 Closing [Text Block] rr_BarChartClosingTextBlock
Highest Quarter: 17.65% (3Q2017)
Lowest Quarter: -20.51% (3Q2015)
Year-to-Date (as of 3/31/20): -35.58%
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-Date
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2020
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn (35.58%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarter:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2017
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.65%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarter:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.51%)
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns Periods Ending December 31, 2019
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)
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  
Management fee rr_ManagementFeesOverAssets 0.65% [1]
Other expenses rr_OtherExpensesOverAssets 0.08%
Total annual fund operating expenses rr_ExpensesOverAssets 0.73%
Expense reimbursement/waiver rr_FeeWaiverOrReimbursementOverAssets none [1]
Total annual fund operating expenses after expense reimbursement/waiver rr_NetExpensesOverAssets 0.73%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 233
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 406
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 906
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 75
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 233
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 406
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 906
Annual Return 2012 rr_AnnualReturn2012 10.30%
Annual Return 2013 rr_AnnualReturn2013 3.58%
Annual Return 2014 rr_AnnualReturn2014 (17.34%)
Annual Return 2015 rr_AnnualReturn2015 (22.02%)
Annual Return 2016 rr_AnnualReturn2016 44.27%
Annual Return 2017 rr_AnnualReturn2017 28.37%
Annual Return 2018 rr_AnnualReturn2018 (6.74%)
Annual Return 2019 rr_AnnualReturn2019 20.08%
1 Year rr_AverageAnnualReturnYear01 20.08%
5 Years rr_AverageAnnualReturnYear05 10.09%
10 Years rr_AverageAnnualReturnYear10
Since Inception rr_AverageAnnualReturnSinceInception 5.61%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 28, 2011
GMO Resources Fund | Class III | Return After Taxes on Distributions  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 19.44%
5 Years rr_AverageAnnualReturnYear05 9.28%
10 Years rr_AverageAnnualReturnYear10
Since Inception rr_AverageAnnualReturnSinceInception 4.45%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 28, 2011
GMO Resources Fund | Class III | Return After Taxes on Distributions and Sale of Fund Shares  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 12.68%
5 Years rr_AverageAnnualReturnYear05 7.92%
10 Years rr_AverageAnnualReturnYear10
Since Inception rr_AverageAnnualReturnSinceInception 4.18%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 28, 2011
GMO Resources Fund | Class III | MSCI ACWI Commodity Producers 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 13.06% [2]
5 Years rr_AverageAnnualReturnYear05 2.19% [2]
10 Years rr_AverageAnnualReturnYear10
Since Inception rr_AverageAnnualReturnSinceInception 0.18% [2]
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 28, 2011
GMO Resources Fund | Class III | 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 26.60% [2]
5 Years rr_AverageAnnualReturnYear05 8.41% [2]
10 Years rr_AverageAnnualReturnYear10
Since Inception rr_AverageAnnualReturnSinceInception 10.65% [2]
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 28, 2011
GMO Resources Fund | Class IV  
Risk/Return: rr_RiskReturnAbstract  
Management fee rr_ManagementFeesOverAssets 0.60% [1]
Other expenses rr_OtherExpensesOverAssets 0.08%
Total annual fund operating expenses rr_ExpensesOverAssets 0.68%
Expense reimbursement/waiver rr_FeeWaiverOrReimbursementOverAssets none [1]
Total annual fund operating expenses after expense reimbursement/waiver rr_NetExpensesOverAssets 0.68%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 69
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 218
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 379
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 847
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 69
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 218
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 379
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 847
1 Year rr_AverageAnnualReturnYear01 20.19%
5 Years rr_AverageAnnualReturnYear05 10.14%
10 Years rr_AverageAnnualReturnYear10
Since Inception rr_AverageAnnualReturnSinceInception 5.32%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 20, 2013
GMO Resources Fund | Class IV | MSCI ACWI Commodity Producers 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 13.06% [2]
5 Years rr_AverageAnnualReturnYear05 2.19% [2]
10 Years rr_AverageAnnualReturnYear10
Since Inception rr_AverageAnnualReturnSinceInception (0.07%) [2]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 20, 2013
GMO Resources Fund | Class IV | 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 26.60% [2]
5 Years rr_AverageAnnualReturnYear05 8.41% [2]
10 Years rr_AverageAnnualReturnYear10
Since Inception rr_AverageAnnualReturnSinceInception 9.07% [2]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 20, 2013
GMO Resources Fund | Class V  
Risk/Return: rr_RiskReturnAbstract  
Management fee rr_ManagementFeesOverAssets 0.585% [1]
Other expenses rr_OtherExpensesOverAssets 0.08%
Total annual fund operating expenses rr_ExpensesOverAssets 0.67%
Expense reimbursement/waiver rr_FeeWaiverOrReimbursementOverAssets none [1]
Total annual fund operating expenses after expense reimbursement/waiver rr_NetExpensesOverAssets 0.67%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 68
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 214
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 373
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 835
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 68
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 214
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 373
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 835
GMO Resources Fund | Class VI  
Risk/Return: rr_RiskReturnAbstract  
Management fee rr_ManagementFeesOverAssets 0.555% [1]
Other expenses rr_OtherExpensesOverAssets 0.08%
Total annual fund operating expenses rr_ExpensesOverAssets 0.64%
Expense reimbursement/waiver rr_FeeWaiverOrReimbursementOverAssets none [1]
Total annual fund operating expenses after expense reimbursement/waiver rr_NetExpensesOverAssets 0.64%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 65
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 205
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 357
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 798
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 65
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 205
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 357
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 798
GMO Resources Fund | Class R6  
Risk/Return: rr_RiskReturnAbstract  
Management fee rr_ManagementFeesOverAssets 0.65% [1]
Other expenses rr_OtherExpensesOverAssets 0.08%
Total annual fund operating expenses rr_ExpensesOverAssets 0.73%
Expense reimbursement/waiver rr_FeeWaiverOrReimbursementOverAssets none [1]
Total annual fund operating expenses after expense reimbursement/waiver rr_NetExpensesOverAssets 0.73%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 233
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 406
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 906
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 75
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 233
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 406
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 906
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess As of the date of this Prospectus, there are no Class R6 shares or Class I shares outstanding or such shares have not been outstanding for a full calendar year.
GMO Resources Fund | Class I  
Risk/Return: rr_RiskReturnAbstract  
Management fee rr_ManagementFeesOverAssets 0.65% [1]
Other expenses rr_OtherExpensesOverAssets 0.16% [3]
Total annual fund operating expenses rr_ExpensesOverAssets 0.81%
Expense reimbursement/waiver rr_FeeWaiverOrReimbursementOverAssets none [1],[3]
Total annual fund operating expenses after expense reimbursement/waiver rr_NetExpensesOverAssets 0.81%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 83
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 259
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 450
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,002
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 83
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 259
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 450
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,002
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess As of the date of this Prospectus, there are no Class R6 shares or Class I shares outstanding or such shares have not been outstanding for a full calendar year.
[1] Includes both management fee of 0.50% and class-specific shareholder service fee, if any, for each class of shares. For additional information about the shareholder service fee applicable to each class of shares of the Fund, please see the table included in the section of the Prospectus entitled "Multiple Classes and Eligibility." 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 (excluding, in the case of Class I shares, any amounts paid for sub-transfer agency, recordkeeping and other administrative services provided by financial intermediaries with respect to Class I shareholders), expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, organizational and start-up expenses, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO is permitted to recover from the Fund, on a class-by-class basis, "Specified Operating Expenses" it has borne or reimbursed (whether through reduction of its fees or otherwise) to the extent that the Fund's "Specified Operating Expenses" later fall below the annualized rate of 0.10% per year or the lower expense limit in effect when GMO seeks to recover the expenses. The Fund, however, is not obligated to pay any such amount more than three years after GMO bore or reimbursed an expense. Any such recovery will not cause the Fund to exceed the annual limitation rate set forth above or the lower expense limit as is in effect at the time GMO seeks to recover 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. These reimbursements and waivers will continue through at least June 30, 2021 and may not be terminated prior to this date without the action or consent of the Trust's Board of Trustees.
[2] MSCI data may not be reproduced or used for any other purpose. MSCI provides no warranties, has not prepared or approved this report, and has no liability hereunder.
[3] Includes estimate of payments for sub-transfer agency, recordkeeping and other administrative services for Class I's initial fiscal year. GMO has contractually agreed to waive its fees with respect to and/or reimburse Class I shares to the extent that amounts paid by the Fund out of the net assets attributable to Class I shares for sub-transfer agency, recordkeeping and other administrative services provided by financial intermediaries with respect to Class I shareholders exceed 0.10% of the average daily net assets attributable to Class I shares. This reimbursement will continue through at least June 30, 2021 and may not be terminated prior to this date without the action or consent of the Trust's Board of Trustees.