v3.25.2
Shareholder Report, Holdings (Details)
May 31, 2025
C000005536 | U.S. Treasury Notes  
Holdings [Line Items]  
Percent of Net Asset Value 18.20%
C000005536 | Federal National Mortgage Assn.  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
C000005536 | Federal Home Loan Mortgage  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
C000005536 | Banco Santander  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
C000005536 | Government National Mortgage Assn.  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000005536 | CVS Health  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
C000005536 | Wells Fargo  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
C000005536 | Crown Castle  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000005536 | Volkswagen Group of America Finance  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000005536 | SBA Tower Trust  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
C000005536 | Corporate Bonds  
Holdings [Line Items]  
Percent of Net Asset Value 43.90%
C000005536 | Asset-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 19.20%
C000005536 | U.S. Government Agency Obligations (Excluding Mortgage-Backed)  
Holdings [Line Items]  
Percent of Net Asset Value 18.60%
C000005536 | Non-U.S. Government Mortgage-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
C000005536 | U.S. Government & Agency Mortgage-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 7.00%
C000005536 | Foreign Government Obligations & Municipalities  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
C000005536 | Securities Lending Collateral  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000005536 | Commercial Paper  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
C000005536 | Other Holdings Grouping  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
C000005537 | U.S. Treasury Notes  
Holdings [Line Items]  
Percent of Net Asset Value 18.20%
C000005537 | Federal National Mortgage Assn.  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
C000005537 | Federal Home Loan Mortgage  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
C000005537 | Banco Santander  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
C000005537 | Government National Mortgage Assn.  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000005537 | CVS Health  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
C000005537 | Wells Fargo  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
C000005537 | Crown Castle  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000005537 | Volkswagen Group of America Finance  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000005537 | SBA Tower Trust  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
C000005537 | Corporate Bonds  
Holdings [Line Items]  
Percent of Net Asset Value 43.90%
C000005537 | Asset-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 19.20%
C000005537 | U.S. Government Agency Obligations (Excluding Mortgage-Backed)  
Holdings [Line Items]  
Percent of Net Asset Value 18.60%
C000005537 | Non-U.S. Government Mortgage-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
C000005537 | U.S. Government & Agency Mortgage-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 7.00%
C000005537 | Foreign Government Obligations & Municipalities  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
C000005537 | Securities Lending Collateral  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000005537 | Commercial Paper  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
C000005537 | Other Holdings Grouping  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
C000166333 | U.S. Treasury Notes  
Holdings [Line Items]  
Percent of Net Asset Value 18.20%
C000166333 | Federal National Mortgage Assn.  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
C000166333 | Federal Home Loan Mortgage  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
C000166333 | Banco Santander  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
C000166333 | Government National Mortgage Assn.  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000166333 | CVS Health  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
C000166333 | Wells Fargo  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
C000166333 | Crown Castle  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000166333 | Volkswagen Group of America Finance  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000166333 | SBA Tower Trust  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
C000166333 | Corporate Bonds  
Holdings [Line Items]  
Percent of Net Asset Value 43.90%
C000166333 | Asset-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 19.20%
C000166333 | U.S. Government Agency Obligations (Excluding Mortgage-Backed)  
Holdings [Line Items]  
Percent of Net Asset Value 18.60%
C000166333 | Non-U.S. Government Mortgage-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
C000166333 | U.S. Government & Agency Mortgage-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 7.00%
C000166333 | Foreign Government Obligations & Municipalities  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
C000166333 | Securities Lending Collateral  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000166333 | Commercial Paper  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
C000166333 | Other Holdings Grouping  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
C000225824 | U.S. Treasury Notes  
Holdings [Line Items]  
Percent of Net Asset Value 18.20%
C000225824 | Federal National Mortgage Assn.  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
C000225824 | Federal Home Loan Mortgage  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
C000225824 | Banco Santander  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
C000225824 | Government National Mortgage Assn.  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000225824 | CVS Health  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
C000225824 | Wells Fargo  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
C000225824 | Crown Castle  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000225824 | Volkswagen Group of America Finance  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000225824 | SBA Tower Trust  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
C000225824 | Corporate Bonds  
Holdings [Line Items]  
Percent of Net Asset Value 43.90%
C000225824 | Asset-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 19.20%
C000225824 | U.S. Government Agency Obligations (Excluding Mortgage-Backed)  
Holdings [Line Items]  
Percent of Net Asset Value 18.60%
C000225824 | Non-U.S. Government Mortgage-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
C000225824 | U.S. Government & Agency Mortgage-Backed Securities  
Holdings [Line Items]  
Percent of Net Asset Value 7.00%
C000225824 | Foreign Government Obligations & Municipalities  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
C000225824 | Securities Lending Collateral  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000225824 | Commercial Paper  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
C000225824 | Other Holdings Grouping  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%