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GMO Global Developed Equity 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]   28.39% 12.19% 11.23% 8.31%
Performance Inception Date Jun. 16, 2005        
After Taxes on Distributions          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   26.68% 10.00% 9.62% 6.88%
After Taxes on Distributions and Sales          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   17.34% 8.92% 8.68% 6.49%
MSCI World Index (Fund benchmark) (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],[2]   21.09% 12.15% 12.17% 8.76%
[1] Returns include a substantial, one-time litigation settlement recovery received on December 16, 2024. This event contributed 1.42% to 2024 annual performance.
[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.