v3.26.1
GMO Asset Allocation Bond Fund Average Annual Total Returns - Class VI
12 Months Ended 60 Months Ended 120 Months Ended 201 Months Ended
Feb. 28, 2026
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Prospectus [Line Items]          
Average Annual Return, Percent   8.82% (2.13%) 1.07% 1.73%
Performance Inception Date Mar. 18, 2009        
After Taxes on Distributions          
Prospectus [Line Items]          
Average Annual Return, Percent   7.65% (3.33%) (0.04%) 0.39%
After Taxes on Distributions and Sales          
Prospectus [Line Items]          
Average Annual Return, Percent   5.22% (2.09%) 0.36% 0.80%
FTSE 3-Month Treasury Bill Index (Fund benchmark) (returns reflect no deduction for fees, expenses, or taxes)[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent   4.40% 3.31% 2.23% 1.35%
Bloomberg U.S. Aggregate Index (reflects no deduction for fees, expenses, or taxes)[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent   7.30% (0.36%) 2.01% 2.90%