XML 66 R131.htm IDEA: XBRL DOCUMENT v3.20.2
Label Element Value
GMO Emerging Country Debt Fund  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading GMO Emerging Country Debt Fund
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
Total return in excess of that of its benchmark, the J.P. Morgan EMBI Global Diversified.
Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
The tables below describe the fees and expenses that you may bear for each class of shares if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund operating expenses (expenses that you bear each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination 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 40% 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 41% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 40.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same as those shown in the table. The one year amounts shown reflect the expense waiver noted in the expense table. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption If you sell your shares
Expense Example, No Redemption, By Year, Caption [Text] rr_ExpenseExampleNoRedemptionByYearCaption If you do not sell your shares
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund invests primarily in non-local currency denominated debt (“external debt”) of emerging market sovereign and quasi-sovereign issuers. “Sovereign” refers to a government and “quasi-sovereign” refers to a governmental agency, political subdivision or other instrumentality or issuer that is majority owned, directly or indirectly, or whose obligations are guaranteed, by a government. Under normal circumstances, the Fund invests directly and indirectly (e.g., through other GMO Funds or derivatives) at least 80% of its assets in debt investments tied economically to emerging countries (see “Name Policies”). In general, the Fund considers “emerging countries” to be countries that are included in the Fund’s benchmark or that have similar national domestic products or default histories to those of countries included in the Fund’s benchmark. The Fund’s performance is likely to be more volatile than that of its benchmark.

The Fund typically gains its investment exposure by purchasing debt investments or by using derivatives, typically credit default swaps. The Fund may invest in debt investments of all credit qualities, including securities that are in default, and may invest in corporate bonds. (The debt investments in which the Fund invests includes below investment grade debt investments, which are sometimes referred to as “high yield” or “junk bonds,” although these terms are not generally used to refer to emerging country debt securities.) The debt investments in which the Fund invests are usually denominated in U.S. dollars, Euros, Japanese yen, Swiss francs, or British pounds sterling, although the Fund also may invest in debt investments that are denominated in local currencies. After hedging, U.S. dollars typically comprise at least 75% of the Fund’s exposures. The Fund typically invests in less liquid debt instruments with the intention of holding them for an extended period of time.

When constructing the portfolio, GMO considers risk at both the portfolio and individual security level and generally takes into account, among other factors, interest rate duration, credit spread duration, liquidity, transaction costs and default duration as well as the idiosyncratic risk of each instrument. When making investment decisions, GMO typically relies more heavily on its assessment of the risk-reward characteristics of the individual instruments in a given country than on its outlook for that particular country. GMO uses fundamental analytical techniques as the basis for its analysis with respect to both individual instrument selection and country outlook, incorporating aspects of ESG (environmental, social, and governance) criteria in so doing. The factors GMO considers and investment methods GMO uses can change over time.

In seeking to achieve the Fund’s investment objective, GMO typically invests a portion of the Fund’s assets in over-the-counter (OTC) and exchange-traded derivatives, including options, swap contracts (including interest rate swaps, total return swaps and credit default swaps), forward currency contracts (including forward contracts on currencies of developed markets), and reverse repurchase agreements. The Fund is not limited in its use of derivatives or in the total notional value of its derivative positions. Leverage is not a principal component of the Fund’s investment strategy. However, because of its derivative positions, the Fund may at times have gross investment exposure in excess of its net assets (i.e. the Fund may be leveraged), and therefore may be subject to heightened risk of loss during those times. 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.

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.

GMO normally seeks to maintain an interest rate duration for the Fund that is similar to that of its benchmark (approximately 7.5 years as of May 31, 2020). For an additional discussion of duration, see “Additional Information About the Funds’ Investment Strategies, Risks, and Expenses — Bond Funds — Duration.”
Risk [Heading] rr_RiskHeading Principal risks of investing in the Fund
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The value of the Fund’s shares changes with the value of the Fund’s investments. Many factors can affect this value, and you may lose money by investing in the Fund. The Fund is a non-diversified investment company under the Investment Company Act of 1940, as amended, and therefore a decline in the market price of a particular security held by the Fund may affect the Fund’s performance more than if the Fund were a diversified investment company. The principal risks of investing in the Fund are summarized below. For a more complete discussion of these risks, see “Additional Information about the Funds’ Investment Strategies, Risks, and Expenses” and “Description of Principal Risks.”

•

Credit Risk – The Fund runs the risk that the issuer or guarantor of a fixed income investment 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. The market price of a fixed income investment will normally decline as a result of the issuer’s, guarantor’s, or obligors’ failure to meet their payment obligations or in anticipation of such failure. In addition, investments in emerging country sovereign or quasi-sovereign debt involve a heightened risk that the issuer responsible for repayment of the debt may be unable or unwilling to pay interest and repay principal when due, and the Fund may lack recourse against the issuer in the event of default. Investments in quasi-sovereign debt also are subject to the risk that the issuer will default independently of its sovereign. 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.

•

Market Risk – Fixed Income – The market price of a fixed income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, or decreased liquidity due, for example, to market uncertainty about the value of a fixed income investment (or class of fixed income investments). In addition, the market prices of emerging country sovereign and quasi-sovereign debt investments can decline due to uncertainty about their credit quality and the reliability of their payment streams.

•

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

•

Derivatives and Short Sales Risk – The use of derivatives involves the risk that their value may not change as expected relative to changes in the value of the underlying assets, 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.

•

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.

•

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.

•

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

•

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

•

Market Disruption and Geopolitical Risk – Geopolitical and other events (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.

•

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

•

Fund of Funds Risk – The Fund is indirectly exposed to all of the risks of an investment in the underlying funds in which it invests, including the risk that those underlying funds will not perform as expected. Because the Fund bears the fees and expenses of the underlying funds in which it invests, the increase in fees and expenses of an underlying fund or a reallocation of the Fund’s investments to underlying funds with higher fees or expenses will increase the Fund’s total expenses.

•

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 market uncertainty about their credit quality and the reliability of their payment streams. Payment streams associated with asset-backed securities held by the Fund depend on many factors (e.g., the cash flow generated by the assets backing the securities, deal structure, creditworthiness of any credit-support provider, and reliability of various other service providers with access to the payment stream), 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.

•

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.

•

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.
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 composite index computed by GMO that tracks historical changes in the Fund's benchmark over time (which has always been comprised of broad-based indices) and the Fund's prior benchmark (which is a broad-based index). Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart. Returns in the table reflect current purchase premiums and redemption fees. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account). After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary. Updated performance information for the Fund is available at www.gmo.com. Past performance (before and after taxes) is not an indication of future performance.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's annual total returns from year to year for the periods indicated and by comparing the Fund's average annual total returns for different calendar periods with those of a composite index computed by GMO that tracks historical changes in the Fund's benchmark over time (which has always been comprised of broad-based indices) and the Fund's prior benchmark (which is a broad-based index).
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.gmo.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading] rr_BarChartHeading Annual Total Returns/Class III Shares Years Ending December 31
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Purchase premiums and redemption fees are not reflected in the bar chart, but are reflected in the table; as a result, the returns in the table are lower than the returns in the bar chart.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Quarter: 12.31% (3Q2010)
Lowest Quarter: -5.33% (2Q2013)
Year-to-Date (as of 3/31/20): -14.48%
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 (14.48%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarter:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2010
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 12.31%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarter:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (5.33%)
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns Periods Ending December 31, 2019
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads Returns in the table reflect current purchase premiums and redemption fees.
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged Effective March 1, 2020, the Fund changed its benchmark from the J.P. Morgan EMBI Global to the J.P. Morgan EMBI Global Diversified because GMO believes the J.P. Morgan EMBI Global Diversified is more appropriate in light of the Fund’s investment strategy. In order to present a performance comparison that tracks changes in the Fund’s benchmark over time, the J.P. Morgan EMBI Global Diversified + (Composite index) is shown in the table above and reflects the performance of  (i) the J.P. Morgan EMBI through 8/31/1995, (ii) the J.P. Morgan EMBI Plus through 12/31/1999, (iii) the J.P. Morgan EMBI Global through 2/29/2020 and (iv) the J.P. Morgan EMBI Global Diversified thereafter.
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant if you are tax-exempt or if you hold your Fund shares through tax-advantaged arrangements (such as a 401(k) plan or individual retirement account).
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for Class III shares only; after-tax returns for other classes will vary.
GMO Emerging Country Debt Fund | Class III  
Risk/Return: rr_RiskReturnAbstract  
Purchase premium (as a percentage of amount invested) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 1.50% [1]
Redemption fee (as a percentage of amount redeemed) rr_RedemptionFeeOverRedemption (1.50%) [1]
Management fee rr_ManagementFeesOverAssets 0.50% [2]
Other expenses rr_OtherExpensesOverAssets 0.04% [3]
Total annual fund operating expenses rr_ExpensesOverAssets 0.54%
Expense waiver rr_FeeWaiverOrReimbursementOverAssets none [2]
Total annual fund operating expenses after expense reimbursement/waiver (Fund and underlying fund expenses) rr_NetExpensesOverAssets 0.54%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 359
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 489
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 631
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,045
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 204
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 320
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 447
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 817
Annual Return 2010 rr_AnnualReturn2010 25.64%
Annual Return 2011 rr_AnnualReturn2011 7.50%
Annual Return 2012 rr_AnnualReturn2012 26.73%
Annual Return 2013 rr_AnnualReturn2013 (1.18%)
Annual Return 2014 rr_AnnualReturn2014 5.98%
Annual Return 2015 rr_AnnualReturn2015 0.02%
Annual Return 2016 rr_AnnualReturn2016 13.86%
Annual Return 2017 rr_AnnualReturn2017 12.48%
Annual Return 2018 rr_AnnualReturn2018 (5.91%)
Annual Return 2019 rr_AnnualReturn2019 14.28%
1 Year rr_AverageAnnualReturnYear01 10.88%
5 Years rr_AverageAnnualReturnYear05 5.97%
10 Years rr_AverageAnnualReturnYear10 9.13%
Since Inception rr_AverageAnnualReturnSinceInception 13.61%
Inception Date rr_AverageAnnualReturnInceptionDate Apr. 19, 1994
GMO Emerging Country Debt Fund | Class III | Return After Taxes on Distributions  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 8.00%
5 Years rr_AverageAnnualReturnYear05 2.90%
10 Years rr_AverageAnnualReturnYear10 5.73%
Since Inception rr_AverageAnnualReturnSinceInception 8.55%
Inception Date rr_AverageAnnualReturnInceptionDate Apr. 19, 1994
GMO Emerging Country Debt Fund | Class III | Return After Taxes on Distributions and Sale of Fund Shares  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 6.43%
5 Years rr_AverageAnnualReturnYear05 3.17%
10 Years rr_AverageAnnualReturnYear10 5.66%
Since Inception rr_AverageAnnualReturnSinceInception 8.62%
Inception Date rr_AverageAnnualReturnInceptionDate Apr. 19, 1994
GMO Emerging Country Debt Fund | Class III | J.P. Morgan EMBI Global Diversified + (Composite index) (Fund benchmark)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 14.42% [4]
5 Years rr_AverageAnnualReturnYear05 5.88% [4]
10 Years rr_AverageAnnualReturnYear10 6.57% [4]
Since Inception rr_AverageAnnualReturnSinceInception 9.85% [4]
Inception Date rr_AverageAnnualReturnInceptionDate Apr. 19, 1994
GMO Emerging Country Debt Fund | Class III | J.P. Morgan EMBI Global (Prior Fund benchmark) (reflects no deduction for fees, expenses, or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 14.42% [4]
5 Years rr_AverageAnnualReturnYear05 5.88% [4]
10 Years rr_AverageAnnualReturnYear10 6.57% [4]
Since Inception rr_AverageAnnualReturnSinceInception 9.91% [4]
Inception Date rr_AverageAnnualReturnInceptionDate Apr. 19, 1994
GMO Emerging Country Debt Fund | Class IV  
Risk/Return: rr_RiskReturnAbstract  
Purchase premium (as a percentage of amount invested) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 1.50% [1]
Redemption fee (as a percentage of amount redeemed) rr_RedemptionFeeOverRedemption (1.50%) [1]
Management fee rr_ManagementFeesOverAssets 0.45% [2]
Other expenses rr_OtherExpensesOverAssets 0.04% [3]
Total annual fund operating expenses rr_ExpensesOverAssets 0.49%
Expense waiver rr_FeeWaiverOrReimbursementOverAssets none [2]
Total annual fund operating expenses after expense reimbursement/waiver (Fund and underlying fund expenses) rr_NetExpensesOverAssets 0.49%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 354
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 473
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 604
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 986
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 199
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 305
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 420
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 757
1 Year rr_AverageAnnualReturnYear01 10.95%
5 Years rr_AverageAnnualReturnYear05 6.02%
10 Years rr_AverageAnnualReturnYear10 9.19%
Since Inception rr_AverageAnnualReturnSinceInception 10.65%
Inception Date rr_AverageAnnualReturnInceptionDate Jan. 09, 1998
GMO Emerging Country Debt Fund | Class IV | J.P. Morgan EMBI Global Diversified + (Composite index) (Fund benchmark)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 14.42% [4]
5 Years rr_AverageAnnualReturnYear05 5.88% [4]
10 Years rr_AverageAnnualReturnYear10 6.57% [4]
Since Inception rr_AverageAnnualReturnSinceInception 8.24% [4]
Inception Date rr_AverageAnnualReturnInceptionDate Jan. 09, 1998
GMO Emerging Country Debt Fund | Class IV | J.P. Morgan EMBI Global (Prior Fund benchmark) (reflects no deduction for fees, expenses, or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 14.42% [4]
5 Years rr_AverageAnnualReturnYear05 5.88% [4]
10 Years rr_AverageAnnualReturnYear10 6.57% [4]
Since Inception rr_AverageAnnualReturnSinceInception 8.31% [4]
Inception Date rr_AverageAnnualReturnInceptionDate Jan. 09, 1998
[1] For additional information, see "Purchase Premiums and Redemption Fees" on page 188 of this Prospectus.
[2] Includes both management fee of 0.35% 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 waive or reduce the Fund's management fees and shareholder service fees to the extent necessary to offset the management fees and shareholder service fees paid to GMO that are directly or indirectly borne by the Fund or a class of shares of the Fund as a result of the Fund's direct or indirect investments in other series of GMO Trust ("GMO Funds"). Management fees and shareholder service fees will not be waived below zero. This waiver will continue through at least June 30, 2021 and may not be terminated prior to this date without the action or consent of the Trust's Board of Trustees.
[3] The amount includes interest expense incurred by the Fund as a result of entering into reverse repurchase agreements and/or margin on cleared swap contracts, if any. "Other expenses" (before addition of interest expense) and interest expense were approximately 0.03% and 0.01%, respectively.
[4] Effective March 1, 2020, the Fund changed its benchmark from the J.P. Morgan EMBI Global to the J.P. Morgan EMBI Global Diversified because GMO believes the J.P. Morgan EMBI Global Diversified is more appropriate in light of the Fund's investment strategy. In order to present a performance comparison that tracks changes in the Fund's benchmark over time, the J.P. Morgan EMBI Global Diversified + (Composite index) is shown in the table above and reflects the performance of (i) the J.P. Morgan EMBI through 8/31/1995, (ii) the J.P. Morgan EMBI Plus through 12/31/1999, (iii) the J.P. Morgan EMBI Global through 2/29/2020 and (iv) the J.P. Morgan EMBI Global Diversified thereafter.