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GMO Strategic Opportunities Allocation Fund Average Annual Total Returns - Class III
 12 Months Ended 60 Months Ended 120 Months Ended 247 Months Ended
Feb. 28, 2026
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Prospectus [Line Items]          
Average Annual Return, Percent [1]   24.80% 9.05% 8.41% 7.37%
Performance Inception Date May 31, 2005        
After Taxes on Distributions          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   20.39% 5.59% 6.02% 5.29%
After Taxes on Distributions and Sales          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   16.57% 6.03% 6.04% 5.38%
GMO Strategic Opportunities Allocation Index (Fund benchmark)[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent [1],[2]   17.60% 9.01% 9.73% 7.61%
MSCI World Index (returns reflect no deduction for fees or expenses, but are net of withholding tax on dividend reinvestments)[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   21.09% 12.15% 12.17% 8.82%
Bloomberg U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes)[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent [1],[3]   7.30% (0.36%) 2.01% 3.18%
[1] Returns include a substantial, one-time litigation settlement recovery received on December 16, 2024. This event contributed 0.94% to 2024 annual performance.
[2] This is a composite index that provides a performance comparison that tracks changes in the Fund’s benchmark over time. See “Fund Benchmarks and Comparative Indices” for the time periods covered by each index included in the composite index.
[3] 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.