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GMO Benchmark-Free Fund Average Annual Total Returns - Class III
 12 Months Ended 60 Months Ended 120 Months Ended 175 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]   24.07% 8.58% 6.63% 6.14%
Performance Inception Date Jun. 15, 2011        
After Taxes on Distributions          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   21.96% 6.74% 5.15% 4.46%
After Taxes on Distributions and Sales          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   14.62% 6.04% 4.71% 4.30%
Consumer Price Index (returns reflect no deduction for fees, expenses, or taxes)[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   2.63% 4.49% 3.20% 2.60%
Bloomberg U.S. Treasury Inflation Notes: 1-10 Year Index (returns reflect no deduction for fees, expenses, or taxes)[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   7.47% 2.52% 3.32% 2.46%
Bloomberg U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes)[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   7.30% (0.36%) 2.01% 2.27%
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],[2]   21.09% 12.15% 12.17% 10.86%
[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] 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.