Label	Element	Value
Prospectus [Line Items]	rr_ProspectusLineItems
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Feb. 28, 2018
Registrant Name	dei_EntityRegistrantName	GMO TRUST
Central Index Key	dei_EntityCentralIndexKey	0000772129
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jun. 29, 2018
Document Effective Date	dei_DocumentEffectiveDate	Jun. 30, 2018
Prospectus Date	rr_ProspectusDate	Jun. 30, 2018
GMO Benchmark-Free Allocation Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GBMFX
GMO Benchmark-Free Allocation Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GBMBX
GMO Global Asset Allocation Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMWAX
GMO Global Equity Allocation Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMGEX
GMO Global Developed Equity Allocation Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GWOAX
GMO Quality Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GQETX
GMO Quality Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GQEFX
GMO Quality Fund \| Class V
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GQLFX
GMO Quality Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GQLOX
GMO Climate Change Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GCCHX
GMO Resources Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GOFIX
GMO Resources Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GOVIX
GMO International Equity Allocation Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GIEAX
GMO International Developed Equity Allocation Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GIOTX
GMO International Equity Fund \| Class II
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMICX
GMO International Equity Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMOIX
GMO International Equity Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMCFX
GMO International Large/Mid Cap Equity Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMIEX
GMO International Large/Mid Cap Equity Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMIRX
GMO International Large/Mid Cap Equity Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GCEFX
GMO Tax-Managed International Equities Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GTMIX
GMO Foreign Small Companies Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMFSX
GMO Foreign Small Companies Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GFSFX
GMO U.S. Equity Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMUEX
GMO U.S. Equity Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMRTX
GMO U.S. Equity Fund \| Class V
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMEQX
GMO U.S. Equity Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMCQX
GMO Emerging Markets Fund \| Class II
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMEMX
GMO Emerging Markets Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMOEX
GMO Emerging Markets Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMEFX
GMO Emerging Markets Fund \| Class V
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GEMVX
GMO Emerging Markets Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GEMMX
GMO Emerging Domestic Opportunities Fund \| Class II
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GEDTX
GMO Emerging Domestic Opportunities Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GEDSX
GMO Emerging Domestic Opportunities Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GEDIX
GMO Emerging Domestic Opportunities Fund \| Class V
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GEDOX
GMO Emerging Domestic Opportunities Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GEDFX
GMO High Yield Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GHVIX
GMO Core Plus Bond Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GUGAX
GMO Core Plus Bond Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GPBFX
GMO Emerging Country Debt Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMCDX
GMO Emerging Country Debt Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMDFX
GMO Opportunistic Income Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMODX
GMO Risk Premium Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMRPX
GMO Risk Premium Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMRVX
GMO Risk Premium Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMOKX
GMO SGM Major Markets Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GSMFX
GMO SGM Major Markets Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GSMJX
GMO SGM Major Markets Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GSMHX
GMO Alpha Only Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GGHEX
GMO Alpha Only Fund \| Class IV
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GAPOX
GMO Asset Allocation Bond Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GMOBX
GMO Asset Allocation Bond Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GABFX
GMO Benchmark-Free Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GBFFX
GMO Implementation Fund \| GMO Implementation Fund
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GIMFX
GMO Special Opportunities Fund \| Class VI
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GSOFX
GMO Strategic Opportunities Allocation Fund \| Class III
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GBATX
GMO U.S. Treasury Fund \| GMO U.S. Treasury Fund
Prospectus [Line Items]	rr_ProspectusLineItems
Trading Symbol	dei_TradingSymbol	GUSTX

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- Definition

The date the document was made available and submitted, in CCYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.

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No definition available.

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- Definition

The date when a document, upon receipt and acceptance, becomes officially effective, in CCYY-MM-DD format. Usually it is a system-assigned date time value, but it may be declared by the submitter in some cases.

+ References

No definition available.

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- Definition

The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

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No definition available.

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- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word "Other".

+ References

No definition available.

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- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12b
-Subsection 1

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- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12b
-Subsection 1

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- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

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- Definition

The date of the prospectus.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 1
-Subsection a
-Paragraph 3

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-Name Form
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-Chapter A

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