Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Prospectus Date	rr_ProspectusDate	Jun. 30, 2023
GMO SGM Major Markets Fund
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	GMO SGM MAJOR MARKETS FUND
Objective [Heading]	rr_ObjectiveHeading	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:bold;">Investment objective</span>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Long-term total return.
Expense [Heading]	rr_ExpenseHeading	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:bold;">Fees and expenses</span>
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, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the table and example below.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:bold;">Annual Fund operating expenses</span> <br/><span style="color:#000000;font-family:Times New Roman;font-size:10pt;margin-left:0%;">(expenses that you bear each year as a percentage of the value of your investment)</span>
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	<span style="font-family:Times New Roman;font-size:8pt;font-style:italic;">June 30, 2024</span>
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:bold;">Portfolio turnover</span>
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 28, 2023, the Fund’s portfolio turnover rate (including the accounts of the Fund’s wholly-owned subsidiary, GMO Alternative Asset SPC Ltd., and excluding short-term investments) was 69% of the average value of its portfolio securities.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	69.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:bold;">Example</span>
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	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:bold;">Principal investment strategies</span>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks long-term total return by taking long and short positions in a range of global equity, bond, currency, and commodity markets using exchange-traded and over-the-counter (OTC) futures, forward currency contracts, swaps, and index options. The Fund also may make direct investments, including in equities and bonds. In constructing the Fund’s portfolio, GMO seeks to take advantage of its proprietary investment models for systematic global tactical asset allocation and market selection. GMO does not maintain a specific interest rate duration for the Fund’s portfolio, and the Fund’s performance is expected to have a low correlation with the performance of major asset classes over a complete market cycle.Fund assets not invested in equities or held as margin for futures, forward transactions or swaps are typically invested in cash or cash-like investments. Such investments include U.S. and non-U.S. government bonds, Treasury floating rate notes, Treasury Separately Traded Registered Interest and Principal Securities (“STRIPS”), Federal Home Loan Bank discount notes, and other agency notes, money market funds unaffiliated with GMO, shares of U.S. Treasury Fund, and the types of investments typically held by money market funds. The Fund also may invest in U.S. and non-U.S. fixed income securities of any credit quality (including below investment grade securities (commonly referred to as “high yield” or “junk bonds”)), maturity or duration.The systematic investment process GMO uses in constructing the Fund’s portfolio is based on the following strategies:•Value-Based Strategies. Value factors compare the price of an asset class or market to the value of a company’s assets less its liabilities. Generally, value strategies include yield analysis and mean reversion analysis.•Sentiment-Based Strategies. Generally, sentiment-based strategies assess factors such as risk aversion, analyst behavior, and momentum.In implementing the Fund’s investment strategy, GMO seeks to take risk positions for the Fund that, in GMO’s view, are proportionate to return opportunities. As a result, during periods when GMO believes return opportunities are high relative to the risks involved, the Fund typically will be exposed to more risks than it would be during periods when GMO believes return opportunities are low relative to the risks involved.GMO may at any time discontinue strategies, add new strategies, or cause the Fund to take positions that deviate from GMO’s investment models as a result of additional research, changing market conditions, or other factors. The factors GMO considers and investment methods GMO uses can change over time.The Fund gains exposure to commodities and some other asset classes by investing through a wholly-owned subsidiary advised by GMO, which does not receive any management or other fees for its services to the subsidiary. The subsidiary invests primarily in commodity-related derivatives (such as futures contracts on commodities and commodity indices and over-the-counter swaps on commodity indices) and fixed income investments but also may invest in any other investment in which the Fund is permitted to invest directly. References in this Prospectus to actions taken by the Fund refer to actions taken by the subsidiary as well as the Fund. The Fund does not invest directly in commodities and commodity-related derivatives.The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. As a result of its derivative positions, the Fund typically has gross investment exposures in excess of its net assets (i.e., the Fund typically is leveraged) and therefore is subject to higher risk of loss than it would be in the absence of such leverage. The Fund’s performance can depend substantially on the performance of assets or indices underlying its derivatives even though it does not own those assets or indices. In addition, the Fund may lend its portfolio securities.
Risk [Heading]	rr_RiskHeading	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:bold;">Principal risks of investing in the Fund</span>
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:bold;">Performance</span>
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund's benchmark (which is a broad-based index) and a composite index computed by GMO. Share classes not shown would have substantially similar annual returns to those below because all share classes invest in the same portfolio of securities. Annual returns vary among share classes to the extent that they bear different expenses. Share classes that bear higher expenses than the share classes shown below 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	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;margin-left:3.76%;">The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s </span><span style="color:#000000;font-family:Times New Roman;font-size:10pt;">annual total returns from year to year for the periods indicated and by comparing the Fund’s average annual total returns for different calendar periods with those of the Fund's benchmark (which is a broad-based index) and a composite index computed by GMO.</span>
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">www.gmo.com</span>
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">Past performance (before and after taxes) is not an indication of future performance.</span>
Bar Chart [Heading]	rr_BarChartHeading	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:bold;margin-left:0%;">Annual Total Returns/Class III Shares*</span> <br/><span style="color:#000000;font-family:Times New Roman;font-size:10pt;">Years Ending December 31</span>
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarter:7.58%4Q 2022Lowest Quarter:-4.53%1Q 2021Year-to-Date:-0.28%As of3/31/2023
Performance Table Heading	rr_PerformanceTableHeading	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:bold;margin-left:0%;">Average Annual Total Returns*</span> <br/><span style="color:#000000;font-family:Times New Roman;font-size:10pt;">Periods Ending December 31, 2022</span>
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">After-tax returns are calculated using the historical highest </span><span style="color:#000000;font-family:Times New Roman;font-size:10pt;">individual federal marginal income tax rates and do not reflect the impact of state and local taxes.</span>
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;"> Actual after-tax returns depend on </span><span style="color:#000000;font-family:Times New Roman;font-size:10pt;">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). </span>
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	<span style="color:#000000;font-family:Times New Roman;font-size:10pt;">After-tax returns are shown </span><span style="color:#000000;font-family:Times New Roman;font-size:10pt;">for Class III shares only; after-tax returns for other classes will vary.</span>
GMO SGM Major Markets Fund | Risk Lose Money [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Many factors can affect this value, and you may lose money by investing in the Fund.
GMO SGM Major Markets Fund | Management and Operational Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Management and Operational Risk – The Fund runs the risk that GMO’s investment techniques will fail to produce intended results.GMO uses quantitative models as part of its investment process. GMO’s models may not accurately predict future market movements. In addition, GMO’s models rely on assumptions and data that are 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.
GMO SGM Major Markets Fund | Market Risk Equities [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Market Risk – Equities – The market price of an equity in the Fund’s portfolio 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 and GMO’s assessment proves to be incorrect, the Fund runs the risk that the market price of the equity will not appreciate or will decline. 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 and interest rates 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.
GMO SGM Major Markets Fund | Currency Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•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.
GMO SGM Major Markets Fund | Commodities Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•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 significantly.
GMO SGM Major Markets Fund | Market Risk Fixed Income [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Market Risk – Fixed Income – The market price of a fixed income investment can decline due to market-related factors, including rising interest or inflation rates and widening credit spreads, or decreased liquidity due, for example, to market uncertainty about the value of a fixed income investment (or class of fixed income investments).
GMO SGM Major Markets Fund | Futures Contracts Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Futures Contracts Risk – The loss to the Fund resulting from its use of futures contracts is potentially unlimited. Futures markets are highly volatile, and the use of futures contracts increases the volatility of the Fund’s net asset value. A liquid secondary market may not exist for any particular futures contract at any particular time, and the Fund may be unable when it wishes to effect closing transactions to terminate its exposure under that contract. When the Fund uses futures contracts for hedging purposes, it runs the risk that changes in the prices of the contracts will not correlate perfectly with changes in the securities, index, or other asset underlying the contracts or movements in the prices of the Fund’s investments that are subject to the hedge. In addition, the Fund may be unable to recover or may be delayed in recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. Foreign futures contracts are often less liquid and more volatile than U.S. futures contracts.
GMO SGM Major Markets Fund | Non-U.S. Investment Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•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. In addition, non-U.S. securities issuers often are not subject to as much regulation as U.S. issuers, and the reporting, recordkeeping, accounting, custody, and auditing standards to which those issuers are subject often are not as rigorous as U.S. standards. In addition, the Fund is subject to taxation by countries other than the United States, 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 securities traded in many non-U.S. securities markets, and the Fund is subject to the risk that its license is 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. The risks above (such as substantial price fluctuations and market instability, illiquidity and lack of regulation) and other risks (e.g., nationalization, expropriation or other confiscation of assets of non-U.S. issuers, difficulties enforcing legal judgments or contractual rights and geopolitical risks) tend to be higher for investments in the securities of companies tied economically to emerging countries. The economies of emerging countries often depend predominantly on only a few industries or revenues from particular commodities and often are more volatile than the economies of developed countries.
GMO SGM Major Markets Fund | Market Disruption and Geopolitical Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Market Disruption and Geopolitical Risk – Geopolitical and other events (e.g., wars, pandemics, sanctions, terrorism) often disrupt securities markets and adversely affect the general economy or particular economies and markets. Those events, as well as other changes in non-U.S. and U.S. economic and political conditions, could exacerbate other risks or otherwise reduce the value of the Fund’s investments.
GMO SGM Major Markets Fund | Derivatives and Short Sales Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•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, leveraging risk, commodities 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 index or underlying securities. The Fund typically creates short investment exposure by selling securities short or 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. Specifically, the net asset value of the Fund’s shares will be adversely affected if the equities or other assets that are the subject of the Fund’s short exposures appreciate in value. The risk of loss associated with derivatives that provide short investment exposure and short sales of securities is theoretically unlimited.
GMO SGM Major Markets Fund | Leveraging Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Leveraging Risk – The use of derivatives, short sales and securities lending can create 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.
GMO SGM Major Markets Fund | Focused Investment Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Focused Investment Risk – Investments focused in countries, regions, asset classes, sectors, industries, currencies, or issuers that are subject to the same or similar risk factors and investments whose market prices are closely correlated are subject to higher overall risk than investments that are more diversified or whose market prices are not as closely correlated.
GMO SGM Major Markets Fund | Counterparty Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•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 collateral or otherwise honor its obligations.
GMO SGM Major Markets Fund | Market Risk Asset Backed Securities [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Market Risk – Asset-Backed Securities – The market price of asset-backed securities, like that of other fixed income investments with complex structures, can decline for a variety of reasons, including investor 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, deal structure, and creditworthiness of any credit-support provider), and a problem in any of these factors can lead to a reduction in the payment stream GMO expected the Fund to receive when the Fund purchased the asset-backed security. The liquidity of asset-backed securities (particularly below investment grade asset-backed securities) may change over time. During periods of deteriorating economic conditions, such as recessions, or periods of rising unemployment, delinquencies and losses generally increase, sometimes dramatically, for asset-backed securities whose underlying assets consist of loans, sales contracts, receivables and other obligations.
GMO SGM Major Markets Fund | Credit Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment (including a sovereign or quasi-sovereign debt issuer) or the obligors of obligations underlying an asset-backed security will be unable or unwilling to satisfy their obligations to pay principal and interest or otherwise to honor their obligations in a timely manner or at all. The market price of a fixed income investment will normally decline as a result of the failure of an issuer, guarantor, or obligor to meet its payment obligations or in anticipation of such a failure. Below investment grade investments have speculative characteristics, and negative changes in economic conditions or other circumstances are more likely to impair the ability of issuers of those investments to make principal and interest payments than issuers of investment grade investments. Investments in distressed or defaulted or other low quality debt investments generally are considered speculative and are subject to substantial risks not normally associated with investments in higher quality securities, including adverse business, financial or economic conditions that lead to their issuers’ payment defaults and insolvency proceedings. In particular, distressed or defaulted obligations might be repaid, if at all, only after lengthy workout or bankruptcy proceedings during which the issuer might not make any interest or other payments, and the Fund may incur additional expenses in its effort to be repaid. If GMO’s assessment of the eventual recovery value of a distressed or defaulted debt investment proves incorrect, the Fund may lose a substantial portion or all of its original investment or may be required to accept cash or instruments worth less than its original investment.
GMO SGM Major Markets Fund | Illiquidity Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Illiquidity Risk – Low trading volume, lack of a market maker, large position size, or legal restrictions increase the risk that the Fund or an underlying fund is limited or prevented from selling particular securities or closing derivative positions at desirable prices.
GMO SGM Major Markets Fund | Fund of Funds Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in its wholly-owned subsidiary and the underlying funds in which it invests, including the risk that its wholly-owned subsidiary and those underlying funds will not perform as expected.
GMO SGM Major Markets Fund | Large Shareholder Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•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 that shareholder or group will require the Fund to sell securities at disadvantageous prices, disrupt the Fund’s operations, or force the Fund’s liquidation.
GMO SGM Major Markets Fund | Class III
Risk Return Abstract	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	1.00%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.14%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.12%)	[1]
Total annual fund operating expenses after expense reimbursement/waiver	rr_NetExpensesOverAssets	1.02%
1 Year	rr_ExpenseExampleYear01	$ 104
3 Years	rr_ExpenseExampleYear03	350
5 Years	rr_ExpenseExampleYear05	616
10 Years	rr_ExpenseExampleYear10	$ 1,375
2013	rr_AnnualReturn2013	6.16%
2014	rr_AnnualReturn2014	3.66%
2015	rr_AnnualReturn2015	0.37%
2016	rr_AnnualReturn2016	4.07%
2017	rr_AnnualReturn2017	3.89%
2018	rr_AnnualReturn2018	(2.13%)
2019	rr_AnnualReturn2019	1.93%
2020	rr_AnnualReturn2020	7.48%
2021	rr_AnnualReturn2021	(5.71%)
2022	rr_AnnualReturn2022	3.57%
Year to Date Return, Label	rr_YearToDateReturnLabel	<span style="font-family:Times New Roman;font-size:10pt;">Year-to-Date:</span>
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2023
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(0.28%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	<span style="font-family:Times New Roman;font-size:10pt;">Highest Quarter:</span>
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2022
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	7.58%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	<span style="font-family:Times New Roman;font-size:10pt;">Lowest Quarter:</span>
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2021
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(4.53%)
1 Year	rr_AverageAnnualReturnYear01	3.57%	[2]
5 Years	rr_AverageAnnualReturnYear05	0.92%	[2]
10 Years	rr_AverageAnnualReturnYear10	2.26%	[2]
Incept.	rr_AverageAnnualReturnSinceInception	2.29%	[2]
Inception Date	rr_AverageAnnualReturnInceptionDate	Apr. 11, 2005
GMO SGM Major Markets Fund | Class IV
Risk Return Abstract	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.95%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.09%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.12%)	[1]
Total annual fund operating expenses after expense reimbursement/waiver	rr_NetExpensesOverAssets	0.97%
1 Year	rr_ExpenseExampleYear01	$ 99
3 Years	rr_ExpenseExampleYear03	335
5 Years	rr_ExpenseExampleYear05	589
10 Years	rr_ExpenseExampleYear10	$ 1,318
GMO SGM Major Markets Fund | Class VI
Risk Return Abstract	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.905%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.16%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.07%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.14%)	[1]
Total annual fund operating expenses after expense reimbursement/waiver	rr_NetExpensesOverAssets	0.93%
1 Year	rr_ExpenseExampleYear01	$ 95
3 Years	rr_ExpenseExampleYear03	326
5 Years	rr_ExpenseExampleYear05	577
10 Years	rr_ExpenseExampleYear10	$ 1,293
1 Year	rr_AverageAnnualReturnYear01	3.69%
5 Years	rr_AverageAnnualReturnYear05	1.02%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.82%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 01, 2015
GMO SGM Major Markets Fund | Class R6
Risk Return Abstract	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	1.00%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.14%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.14%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.12%)	[1]
Total annual fund operating expenses after expense reimbursement/waiver	rr_NetExpensesOverAssets	1.02%
1 Year	rr_ExpenseExampleYear01	$ 104
3 Years	rr_ExpenseExampleYear03	350
5 Years	rr_ExpenseExampleYear05	616
10 Years	rr_ExpenseExampleYear10	$ 1,375
GMO SGM Major Markets Fund | Class I
Risk Return Abstract	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	1.00%	[1]
Other expenses	rr_OtherExpensesOverAssets	0.30%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.30%
Expense reimbursement/waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.18%)	[1],[3]
Total annual fund operating expenses after expense reimbursement/waiver	rr_NetExpensesOverAssets	1.12%
1 Year	rr_ExpenseExampleYear01	$ 114
3 Years	rr_ExpenseExampleYear03	394
5 Years	rr_ExpenseExampleYear05	696
10 Years	rr_ExpenseExampleYear10	$ 1,552
1 Year	rr_AverageAnnualReturnYear01	3.47%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 23, 2020
GMO SGM Major Markets Fund | Return After Taxes on Distributions | Class III
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.72%	[2]
5 Years	rr_AverageAnnualReturnYear05	(0.11%)	[2]
10 Years	rr_AverageAnnualReturnYear10	1.39%	[2]
Incept.	rr_AverageAnnualReturnSinceInception	1.80%	[2]
GMO SGM Major Markets Fund | Return After Taxes on Distributions and Sale of Shares | Class III
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	2.78%
5 Years	rr_AverageAnnualReturnYear05	0.48%
10 Years	rr_AverageAnnualReturnYear10	1.54%
Incept.	rr_AverageAnnualReturnSinceInception	1.69%
GMO SGM Major Markets Fund | FTSE 3-Month Treasury Bill Index (returns reflect no deduction for fees, expenses, or taxes) | Class III
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.50%
5 Years	rr_AverageAnnualReturnYear05	1.25%
10 Years	rr_AverageAnnualReturnYear10	0.74%
Incept.	rr_AverageAnnualReturnSinceInception	1.21%
GMO SGM Major Markets Fund | FTSE 3-Month Treasury Bill Index (returns reflect no deduction for fees, expenses, or taxes) | Class VI
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.50%
5 Years	rr_AverageAnnualReturnYear05	1.25%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.04%
GMO SGM Major Markets Fund | FTSE 3-Month Treasury Bill Index (returns reflect no deduction for fees, expenses, or taxes) | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.50%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.69%
GMO SGM Major Markets Fund | FTSE 3-Month Treasury Bill Index +++ (Composite Index) | Class III
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.50%
5 Years	rr_AverageAnnualReturnYear05	1.25%
10 Years	rr_AverageAnnualReturnYear10	0.74%
Incept.	rr_AverageAnnualReturnSinceInception	1.23%
GMO SGM Major Markets Fund | FTSE 3-Month Treasury Bill Index +++ (Composite Index) | Class VI
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.50%
5 Years	rr_AverageAnnualReturnYear05	1.25%
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	1.04%
GMO SGM Major Markets Fund | FTSE 3-Month Treasury Bill Index +++ (Composite Index) | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.50%
5 Years	rr_AverageAnnualReturnYear05
10 Years	rr_AverageAnnualReturnYear10
Incept.	rr_AverageAnnualReturnSinceInception	0.69%

[1] Includes both management fee of 0.85% 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 0.02% 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 for the benefit of Class I shareholders), expenses of non-investment related legal services provided to the Fund by or at the direction of GMO, federal securities law filing expenses, printing expenses, state and federal registration fees and custody expenses. GMO also has contractually agreed to waive or reduce the Fund’s management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund’s direct or indirect investments in other series of GMO Trust (“GMO Funds”). Management fees and shareholder service fees will not be waived below zero as a result of this waiver. These reimbursements and waivers will continue through at least June 30, 2024 and may not be terminated prior to this date without the action or consent of the Trust’s Board of Trustees.

[2] After-tax returns do not reflect distributions made by the Fund for all periods prior to December 1, 2015, the date on which the Fund elected to change its U.S. federal income tax status from that of a partnership to a corporation. Further, as described in “Distributions and Taxes,” the Fund elected to be treated and intends 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.

[3] Includes payments for sub-transfer agency, recordkeeping and other administrative services provided by financial intermediaries for the benefit of Class I shareholders. 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 for the benefit of 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, 2024 and may not be terminated prior to this date without the action or consent of the Trust’s Board of Trustees.