v3.26.1
GMO International Opportunistic Value Fund Average Annual Total Returns
 12 Months Ended 21 Months Ended 27 Months Ended 29 Months Ended 60 Months Ended 120 Months Ended 329 Months Ended
Feb. 28, 2026
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Class III                
Prospectus [Line Items]                
Average Annual Return, Percent [1],[2]   46.29%       12.64% 9.25% 7.10%
Performance Inception Date Jul. 29, 1998              
Class III | After Taxes on Distributions                
Prospectus [Line Items]                
Average Annual Return, Percent [1],[2]   37.79%       9.59% 7.38% 6.06%
Class III | After Taxes on Distributions and Sales                
Prospectus [Line Items]                
Average Annual Return, Percent [1],[2]   30.20%       9.25% 7.08% 5.89%
Class III | MSCI World ex USA Value 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],[3]   42.23%       13.95% 9.16% 6.06%
Class III | MSCI World ex USA 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],[3]   31.85%       9.47% 8.55% 5.52%
Class IV                
Prospectus [Line Items]                
Average Annual Return, Percent [1],[2]   46.26%   24.40%    
Performance Inception Date Sep. 25, 2023              
Class IV | MSCI World ex USA Value 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],[3]   42.23%   24.29%        
Class IV | MSCI World ex USA 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],[3]   31.85%   20.22%        
Class R6                
Prospectus [Line Items]                
Average Annual Return, Percent [1],[2]   46.29% 24.82%      
Performance Inception Date Apr. 08, 2024              
Class R6 | MSCI World ex USA Value 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]   42.23% 24.09%          
Class R6 | MSCI World ex USA 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]   31.85% 17.11%          
Class I                
Prospectus [Line Items]                
Average Annual Return, Percent [1],[2]   46.08%     22.91%  
Performance Inception Date Aug. 14, 2023              
Class I | MSCI World ex USA Value 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],[3]   42.23%     22.98%      
Class I | MSCI World ex USA 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],[3]   31.85%     17.69%      
[1] Returns include a substantial, one-time litigation settlement recovery received on December 16, 2024. This event contributed 0.44% to 2024 annual performance.
[2] The performance information (before and after taxes) for all periods prior to May 22, 2023 was achieved prior to the change in the Fund’s investment objective and principal investment strategies, effective May 22, 2023.
[3] Index performance from inception is presented beginning on July 31, 1998 due to the unavailability of daily index returns prior to 2001. 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.