v3.26.1
Average Annual Total Returns
 12 Months Ended 60 Months Ended 120 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Bloomberg US Aggregate Bond Index(reflects no deduction for fees, expenses or taxes)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent [1] 7.30% (0.36%) 2.01%
Bloomberg US Mortgage Backed Securities Index(reflects no deduction for fees, expenses or taxes)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent [2] 8.58% 0.15% 1.59%
IS      
Prospectus [Line Items]      
Average Annual Return, Percent 8.52% (0.31%) 1.19%
IS | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 6.89% (1.32%) 0.23%
IS | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 5.01% (0.67%) 0.49%
SS      
Prospectus [Line Items]      
Average Annual Return, Percent 8.31% (0.51%) 0.99%
[1] The Bloomberg US Aggregate Bond Index is a broad-based benchmark that measures the investment-grade, U.S. dollar-denominated, fixed-rate taxable bond market.
[2] The Bloomberg US Mortgage Backed Securities Index tracks agency mortgage-backed pass-through securities (both fixed-rate and hybrid ARM) guaranteed by Ginnie Mae (GNMA), Fannie Mae (FNMA) and Freddie Mac (FHLMC).