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GMO International Developed Equity Allocation Fund Average Annual Total Returns
 12 Months Ended 47 Months Ended 60 Months Ended 120 Months Ended 223 Months Ended
Feb. 28, 2025
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
Class III            
Prospectus [Line Items]            
Average Annual Return, Percent   10.64%   6.95% 5.47% 4.44%
Performance Inception Date Jun. 05, 2006          
Class III | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent   9.28%   5.50% 4.45% 3.39%
Class III | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent   7.12%   5.17% 4.24% 3.44%
Class III | MSCI EAFE 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]   3.82%   4.73% 5.20% 3.87%
Class R6            
Prospectus [Line Items]            
Average Annual Return, Percent   10.64% 5.94%  
Performance Inception Date Jan. 22, 2021          
Class R6 | MSCI EAFE 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]   3.82% 3.39%      
[1] 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.