v3.26.1
Loomis Sayles Global Allocation Portfolio Average Annual Total Returns
12 Months Ended 60 Months Ended 120 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
MSCI All Country World Index (reflects no deduction for mutual fund fees or expenses)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 22.34% 11.19% 11.72%
Bloomberg Global Aggregate Index (reflects no deduction for mutual fund fees or expenses)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 8.17% (2.15%) 1.26%
FTSE World Government Bond Index (reflects no deduction for mutual fund fees or expenses)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 7.55% (3.53%) 0.54%
MSCI World Index (reflects no deduction for mutual fund fees or expenses)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 21.09% 12.15% 12.17%
Class A      
Prospectus [Line Items]      
Average Annual Return, Percent 12.94% 6.52% 9.50%
Class B      
Prospectus [Line Items]      
Average Annual Return, Percent 12.59% 6.25% 9.22%