v3.26.1
GMO-Usonian Japan Value Creation Fund Average Annual Total Returns
 12 Months Ended 48 Months Ended 55 Months Ended 60 Months Ended 64 Months Ended 120 Months Ended
Feb. 28, 2026
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   31.42% 10.83%    
Performance Inception Date Dec. 30, 2021            
Class III | Tokyo Stock Price Index (Total Return) (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]   25.64% 8.21%        
Class VI              
Prospectus [Line Items]              
Average Annual Return, Percent   31.59%     8.82% 11.54%
Performance Inception Date Sep. 14, 2020            
Class VI | After Taxes on Distributions              
Prospectus [Line Items]              
Average Annual Return, Percent   29.70%     6.65% 9.37%
Class VI | After Taxes on Distributions and Sales              
Prospectus [Line Items]              
Average Annual Return, Percent   19.67%     6.14% 8.40%
Class VI | Tokyo Stock Price Index (Total Return) (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]   25.64%     6.68% 8.74%  
Class I              
Prospectus [Line Items]              
Average Annual Return, Percent   31.30%   7.61%  
Performance Inception Date Jun. 07, 2021            
Class I | Tokyo Stock Price Index (Total Return) (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]   25.64%   6.53%      
[1] TOPIX data may not be reproduced or used for any other purpose. TOPIX provides no warranties, has not prepared or approved this report, and has no liability hereunder.