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GMO Benchmark-Free Allocation Fund Annual Total Returns
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
GMO Benchmark-Free Allocation Fund | Class III                    
Prospectus [Line Items]                    
Annual Return [Percent] 4.27% 13.40% (2.26%) 2.96% (2.49%) 11.62% (5.35%) 13.04% 3.40% (4.28%)