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GMO Alternative Allocation Fund Average Annual Total Returns
 12 Months Ended 60 Months Ended 76 Months Ended 80 Months Ended 120 Months Ended
Feb. 28, 2026
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Class VI            
Prospectus [Line Items]            
Average Annual Return, Percent [1]   15.16% 3.19%   2.76%
Performance Inception Date May 01, 2019          
Class VI | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent [1]   11.69% 1.69%   1.35%
Class VI | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent [1]   9.39% 1.95%   1.62%
Class VI | FTSE 3-Month Treasury Bill 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]   4.40% 3.31%   2.78%  
Class VI | 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%)   1.64%  
Class I            
Prospectus [Line Items]            
Average Annual Return, Percent [1]   14.82% 2.91% 2.49%  
Performance Inception Date Sep. 04, 2019          
Class I | FTSE 3-Month Treasury Bill 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]   4.40% 3.31% 2.80%    
Class I | 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%) 0.76%    
[1] The performance information (before and after taxes) for all periods prior to January 31, 2025 was achieved prior to the change in the Fund's principal investment strategies, effective January 31, 2025.