v3.26.1
S000001256 [Member] Average Annual Total Returns
12 Months Ended 60 Months Ended 120 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Bloomberg Universal Index (reflects no deduction for fees, expenses, or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 7.58% 0.06% 2.44%
Bloomberg U.S. Corporate High Yield 2% Issuer Capped Index (reflects no deduction for fees, expenses, or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 8.62% 4.50% 6.52%
HIGH YIELD FIXED INCOME FUND      
Prospectus [Line Items]      
Average Annual Return, Percent 8.74% 4.49% 5.83%
HIGH YIELD FIXED INCOME FUND | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 5.73% 1.83% 3.16%
HIGH YIELD FIXED INCOME FUND | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 5.11% 2.23% 3.27%