v3.26.1
Shareholder Report, Holdings (Details)
Mar. 31, 2026
C000202747 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.60% [1]
C000202747 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20% [1]
C000202747 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.10% [1]
C000202747 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00% [1]
C000202747 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.00% [1]
C000202747 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 47.80% [1]
C000202747 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.30% [1]
C000202747 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000202747 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000202747 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.70%
C000202747 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 49.30%
C000202747 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000202747 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [2]
C000202747 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000202747 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000202747 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000202747 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000202747 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.90%
C000033991 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.60% [3]
C000033991 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20% [3]
C000033991 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.10% [3]
C000033991 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00% [3]
C000033991 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.00% [3]
C000033991 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 47.80% [3]
C000033991 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.30% [3]
C000033991 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000033991 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000033991 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.70%
C000033991 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 49.30%
C000033991 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000033991 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [4]
C000033991 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000033991 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033991 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000033991 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000033991 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.90%
C000014635 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.60% [5]
C000014635 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20% [5]
C000014635 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.10% [5]
C000014635 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00% [5]
C000014635 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.00% [5]
C000014635 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 47.80% [5]
C000014635 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.30% [5]
C000014635 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000014635 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000014635 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.70%
C000014635 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 49.30%
C000014635 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000014635 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [6]
C000014635 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000014635 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000014635 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000014635 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000014635 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.90%
C000079556 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.60% [7]
C000079556 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20% [7]
C000079556 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.10% [7]
C000079556 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00% [7]
C000079556 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.00% [7]
C000079556 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 47.80% [7]
C000079556 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.30% [7]
C000079556 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000079556 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000079556 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.70%
C000079556 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 49.30%
C000079556 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000079556 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [8]
C000079556 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000079556 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000079556 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000079556 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000079556 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.90%
C000162549 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.60% [9]
C000162549 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20% [9]
C000162549 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.10% [9]
C000162549 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00% [9]
C000162549 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.00% [9]
C000162549 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 47.80% [9]
C000162549 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.30% [9]
C000162549 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000162549 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000162549 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.70%
C000162549 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 49.30%
C000162549 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000162549 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [10]
C000162549 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000162549 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000162549 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000162549 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000162549 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.90%
C000033992 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.60% [11]
C000033992 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20% [11]
C000033992 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.10% [11]
C000033992 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00% [11]
C000033992 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.00% [11]
C000033992 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 47.80% [11]
C000033992 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.30% [11]
C000033992 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000033992 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000033992 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.70%
C000033992 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 49.30%
C000033992 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000033992 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [12]
C000033992 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000033992 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033992 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000033992 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000033992 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.90%
C000033995 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.10%
C000033995 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.40%
C000033995 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20%
C000033995 [Member] | Short Term Variable Rate Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 30.30%
C000162551 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.10%
C000162551 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.40%
C000162551 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20%
C000162551 [Member] | Short Term Variable Rate Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 30.30%
C000079558 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.10%
C000079558 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.40%
C000079558 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20%
C000079558 [Member] | Short Term Variable Rate Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 30.30%
C000014638 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.10%
C000014638 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.40%
C000014638 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20%
C000014638 [Member] | Short Term Variable Rate Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 30.30%
C000033994 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.10%
C000033994 [Member] | Short Term Government Agency Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.40%
C000033994 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20%
C000033994 [Member] | Short Term Variable Rate Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 30.30%
C000202755 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [13]
C000202755 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.30% [13]
C000202755 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40% [13]
C000202755 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.80% [13]
C000202755 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20% [13]
C000202755 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 41.10% [13]
C000202755 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30% [13]
C000202755 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000202755 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000202755 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 21.90%
C000202755 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 37.60%
C000202755 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000202755 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000202755 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 39.00%
C000033275 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [14]
C000033275 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.30% [14]
C000033275 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40% [14]
C000033275 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.80% [14]
C000033275 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20% [14]
C000033275 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 41.10% [14]
C000033275 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30% [14]
C000033275 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000033275 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033275 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 21.90%
C000033275 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 37.60%
C000033275 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000033275 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000033275 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 39.00%
C000033276 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [15]
C000033276 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.30% [15]
C000033276 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40% [15]
C000033276 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.80% [15]
C000033276 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20% [15]
C000033276 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 41.10% [15]
C000033276 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30% [15]
C000033276 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000033276 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033276 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 21.90%
C000033276 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 37.60%
C000033276 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000033276 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000033276 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 39.00%
C000079571 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [16]
C000079571 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.30% [16]
C000079571 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40% [16]
C000079571 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.80% [16]
C000079571 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20% [16]
C000079571 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 41.10% [16]
C000079571 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30% [16]
C000079571 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000079571 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000079571 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 21.90%
C000079571 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 37.60%
C000079571 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000079571 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000079571 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 39.00%
C000162566 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [17]
C000162566 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.30% [17]
C000162566 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40% [17]
C000162566 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.80% [17]
C000162566 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20% [17]
C000162566 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 41.10% [17]
C000162566 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30% [17]
C000162566 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000162566 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000162566 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 21.90%
C000162566 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 37.60%
C000162566 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000162566 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000162566 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 39.00%
C000033274 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [18]
C000033274 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.30% [18]
C000033274 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40% [18]
C000033274 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.80% [18]
C000033274 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.20% [18]
C000033274 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 41.10% [18]
C000033274 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30% [18]
C000033274 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000033274 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033274 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 21.90%
C000033274 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 37.60%
C000033274 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000033274 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000033274 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 39.00%
C000033277 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 93.10% [19]
C000033277 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.20% [19]
C000033277 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10% [19]
C000033277 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60% [19]
C000033277 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [19]
C000033277 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000033277 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000033277 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000033277 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033277 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000033277 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000033277 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 91.00%
C000162567 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 93.10% [20]
C000162567 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.20% [20]
C000162567 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10% [20]
C000162567 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60% [20]
C000162567 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [20]
C000162567 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000162567 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000162567 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000162567 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000162567 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000162567 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000162567 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 91.00%
C000079572 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 93.10% [21]
C000079572 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.20% [21]
C000079572 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10% [21]
C000079572 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60% [21]
C000079572 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [21]
C000079572 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000079572 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000079572 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000079572 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000079572 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000079572 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000079572 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 91.00%
C000033279 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 93.10% [22]
C000033279 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.20% [22]
C000033279 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10% [22]
C000033279 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60% [22]
C000033279 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [22]
C000033279 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000033279 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000033279 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000033279 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033279 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000033279 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000033279 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 91.00%
C000033278 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 93.10% [23]
C000033278 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.20% [23]
C000033278 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10% [23]
C000033278 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60% [23]
C000033278 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [23]
C000033278 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000033278 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000033278 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000033278 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033278 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000033278 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000033278 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 91.00%
C000202756 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 93.10% [24]
C000202756 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.20% [24]
C000202756 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10% [24]
C000202756 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60% [24]
C000202756 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [24]
C000202756 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000202756 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000202756 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000202756 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000202756 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.60%
C000202756 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000202756 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 91.00%
C000202758 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.30% [25]
C000202758 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.30% [25]
C000202758 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.20% [25]
C000202758 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.00% [25]
C000202758 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.70% [25]
C000202758 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.90% [25]
C000202758 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60% [25]
C000202758 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000202758 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000202758 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.00%
C000202758 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 40.90%
C000202758 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50% [26]
C000202758 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000202758 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000202758 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000202758 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000202758 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
C000033284 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.30% [27]
C000033284 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.30% [27]
C000033284 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.20% [27]
C000033284 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.00% [27]
C000033284 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.70% [27]
C000033284 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.90% [27]
C000033284 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60% [27]
C000033284 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000033284 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000033284 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.00%
C000033284 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 40.90%
C000033284 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50% [28]
C000033284 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000033284 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033284 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000033284 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000033284 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
C000033285 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.30% [29]
C000033285 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.30% [29]
C000033285 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.20% [29]
C000033285 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.00% [29]
C000033285 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.70% [29]
C000033285 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.90% [29]
C000033285 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60% [29]
C000033285 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000033285 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000033285 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.00%
C000033285 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 40.90%
C000033285 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50% [30]
C000033285 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000033285 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033285 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000033285 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000033285 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
C000079574 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.30% [31]
C000079574 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.30% [31]
C000079574 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.20% [31]
C000079574 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.00% [31]
C000079574 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.70% [31]
C000079574 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.90% [31]
C000079574 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60% [31]
C000079574 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000079574 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000079574 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.00%
C000079574 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 40.90%
C000079574 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50% [32]
C000079574 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000079574 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000079574 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000079574 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000079574 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
C000162569 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.30% [33]
C000162569 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.30% [33]
C000162569 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.20% [33]
C000162569 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.00% [33]
C000162569 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.70% [33]
C000162569 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.90% [33]
C000162569 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60% [33]
C000162569 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000162569 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000162569 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.00%
C000162569 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 40.90%
C000162569 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50% [34]
C000162569 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000162569 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000162569 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000162569 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000162569 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
C000033283 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.30% [35]
C000033283 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.30% [35]
C000033283 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.20% [35]
C000033283 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.00% [35]
C000033283 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.70% [35]
C000033283 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.90% [35]
C000033283 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60% [35]
C000033283 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000033283 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000033283 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.00%
C000033283 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 40.90%
C000033283 [Member] | Investment companies [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.50% [36]
C000033283 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000033283 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033283 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000033283 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.20%
C000033283 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.40%
C000033286 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.70% [37]
C000033286 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60% [37]
C000033286 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [37]
C000033286 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 27.60% [37]
C000033286 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 54.70% [37]
C000033286 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.30% [37]
C000033286 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 99.40%
C000033286 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000033286 [Member] | Rights Warrants [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000162570 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.70% [38]
C000162570 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60% [38]
C000162570 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [38]
C000162570 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 27.60% [38]
C000162570 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 54.70% [38]
C000162570 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.30% [38]
C000162570 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 99.40%
C000162570 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000162570 [Member] | Rights Warrants [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000033287 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.70% [39]
C000033287 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60% [39]
C000033287 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.10% [39]
C000033287 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 27.60% [39]
C000033287 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 54.70% [39]
C000033287 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.30% [39]
C000033287 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 99.40%
C000033287 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000033287 [Member] | Rights Warrants [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000202762 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90% [40]
C000202762 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.70% [40]
C000202762 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [40]
C000202762 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.00% [40]
C000202762 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 71.60% [40]
C000202762 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [40]
C000202762 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000202762 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000202762 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.40%
C000202762 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 70.40%
C000202762 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.90%
C000202762 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.40%
C000079523 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90% [41]
C000079523 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.70% [41]
C000079523 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [41]
C000079523 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.00% [41]
C000079523 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 71.60% [41]
C000079523 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [41]
C000079523 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000079523 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000079523 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.40%
C000079523 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 70.40%
C000079523 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.90%
C000079523 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.40%
C000079524 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90% [42]
C000079524 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.70% [42]
C000079524 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [42]
C000079524 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.00% [42]
C000079524 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 71.60% [42]
C000079524 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [42]
C000079524 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000079524 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000079524 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.40%
C000079524 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 70.40%
C000079524 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.90%
C000079524 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.40%
C000079525 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90% [43]
C000079525 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.70% [43]
C000079525 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [43]
C000079525 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.00% [43]
C000079525 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 71.60% [43]
C000079525 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [43]
C000079525 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000079525 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000079525 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.40%
C000079525 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 70.40%
C000079525 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.90%
C000079525 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.40%
C000162579 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90% [44]
C000162579 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.70% [44]
C000162579 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [44]
C000162579 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.00% [44]
C000162579 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 71.60% [44]
C000162579 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [44]
C000162579 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000162579 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000162579 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.40%
C000162579 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 70.40%
C000162579 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.90%
C000162579 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.40%
C000079526 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.90% [45]
C000079526 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.70% [45]
C000079526 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [45]
C000079526 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.00% [45]
C000079526 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 71.60% [45]
C000079526 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00% [45]
C000079526 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000079526 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000079526 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.40%
C000079526 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 70.40%
C000079526 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.90%
C000079526 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.40%
C000117723 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.00% [46]
C000117723 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.10% [46]
C000117723 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60% [46]
C000117723 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.70% [46]
C000117723 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.70% [46]
C000117723 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 52.60% [46]
C000117723 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.30% [46]
C000117723 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000117723 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.40%
C000117723 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.50%
C000117723 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 55.00%
C000117723 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000117723 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000117723 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000117723 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 30.10%
C000162598 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.00% [47]
C000162598 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.10% [47]
C000162598 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60% [47]
C000162598 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.70% [47]
C000162598 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.70% [47]
C000162598 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 52.60% [47]
C000162598 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.30% [47]
C000162598 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000162598 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.40%
C000162598 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.50%
C000162598 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 55.00%
C000162598 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000162598 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000162598 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000162598 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 30.10%
C000117722 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.00% [48]
C000117722 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.10% [48]
C000117722 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60% [48]
C000117722 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.70% [48]
C000117722 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.70% [48]
C000117722 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 52.60% [48]
C000117722 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.30% [48]
C000117722 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000117722 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.40%
C000117722 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.50%
C000117722 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 55.00%
C000117722 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000117722 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000117722 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000117722 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 30.10%
C000117721 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.00% [49]
C000117721 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.10% [49]
C000117721 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60% [49]
C000117721 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.70% [49]
C000117721 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.70% [49]
C000117721 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 52.60% [49]
C000117721 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.30% [49]
C000117721 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000117721 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.40%
C000117721 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.50%
C000117721 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 55.00%
C000117721 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000117721 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000117721 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000117721 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 30.10%
C000117724 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.00% [50]
C000117724 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.10% [50]
C000117724 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60% [50]
C000117724 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.70% [50]
C000117724 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.70% [50]
C000117724 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 52.60% [50]
C000117724 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.30% [50]
C000117724 [Member] | Short Term Treasury Debt [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000117724 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.40%
C000117724 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.50%
C000117724 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 55.00%
C000117724 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000117724 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20%
C000117724 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000117724 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 30.10%
C000202767 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.50% [51]
C000202767 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [51]
C000202767 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.40% [51]
C000202767 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.50% [51]
C000202767 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 75.00% [51]
C000202767 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10% [51]
C000202767 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000202767 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000202767 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 74.60%
C000202767 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000202767 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.90%
C000158753 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.50% [52]
C000158753 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [52]
C000158753 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.40% [52]
C000158753 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.50% [52]
C000158753 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 75.00% [52]
C000158753 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10% [52]
C000158753 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000158753 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000158753 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 74.60%
C000158753 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000158753 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.90%
C000158750 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.50% [53]
C000158750 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [53]
C000158750 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.40% [53]
C000158750 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.50% [53]
C000158750 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 75.00% [53]
C000158750 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10% [53]
C000158750 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000158750 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000158750 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 74.60%
C000158750 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000158750 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.90%
C000158751 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.50% [54]
C000158751 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [54]
C000158751 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.40% [54]
C000158751 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.50% [54]
C000158751 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 75.00% [54]
C000158751 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10% [54]
C000158751 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000158751 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000158751 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 74.60%
C000158751 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000158751 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.90%
C000162603 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.50% [55]
C000162603 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [55]
C000162603 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.40% [55]
C000162603 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.50% [55]
C000162603 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 75.00% [55]
C000162603 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10% [55]
C000162603 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000162603 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000162603 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 74.60%
C000162603 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000162603 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.90%
C000158752 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.50% [56]
C000158752 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [56]
C000158752 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.40% [56]
C000158752 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.50% [56]
C000158752 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 75.00% [56]
C000158752 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10% [56]
C000158752 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000158752 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.00%
C000158752 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 74.60%
C000158752 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000158752 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.90%
C000205813 [Member] | Supranational [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20%
C000205813 [Member] | Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10%
C000205813 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.70% [57]
C000205813 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.80% [57]
C000205813 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40% [57]
C000205813 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.50% [57]
C000205813 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.50% [57]
C000205813 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.50% [57]
C000205813 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.60% [57]
C000205813 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000205813 [Member] | ECUADOR  
Holdings [Line Items]  
Percent of Total Investments 1.00%
C000205813 [Member] | GERMANY  
Holdings [Line Items]  
Percent of Total Investments 2.90%
C000205813 [Member] | IRELAND  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000205813 [Member] | MEXICO  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205813 [Member] | UNITED ARAB EMIRATES  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000205813 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000205813 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 73.50%
C000205813 [Member] | TÜRKIYE  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205813 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.00%
C000205813 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.20%
C000205813 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 20.70%
C000205813 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000205813 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205813 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.90%
C000205813 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.50%
C000205815 [Member] | Supranational [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20%
C000205815 [Member] | Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10%
C000205815 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.70% [58]
C000205815 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.80% [58]
C000205815 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40% [58]
C000205815 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.50% [58]
C000205815 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.50% [58]
C000205815 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.50% [58]
C000205815 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.60% [58]
C000205815 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000205815 [Member] | ECUADOR  
Holdings [Line Items]  
Percent of Total Investments 1.00%
C000205815 [Member] | GERMANY  
Holdings [Line Items]  
Percent of Total Investments 2.90%
C000205815 [Member] | IRELAND  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000205815 [Member] | MEXICO  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205815 [Member] | UNITED ARAB EMIRATES  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000205815 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000205815 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 73.50%
C000205815 [Member] | TÜRKIYE  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205815 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.00%
C000205815 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.20%
C000205815 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 20.70%
C000205815 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000205815 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205815 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.90%
C000205815 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.50%
C000205812 [Member] | Supranational [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20%
C000205812 [Member] | Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10%
C000205812 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.70% [59]
C000205812 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.80% [59]
C000205812 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40% [59]
C000205812 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.50% [59]
C000205812 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.50% [59]
C000205812 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.50% [59]
C000205812 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.60% [59]
C000205812 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000205812 [Member] | ECUADOR  
Holdings [Line Items]  
Percent of Total Investments 1.00%
C000205812 [Member] | GERMANY  
Holdings [Line Items]  
Percent of Total Investments 2.90%
C000205812 [Member] | IRELAND  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000205812 [Member] | MEXICO  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205812 [Member] | UNITED ARAB EMIRATES  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000205812 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000205812 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 73.50%
C000205812 [Member] | TÜRKIYE  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205812 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.00%
C000205812 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.20%
C000205812 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 20.70%
C000205812 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000205812 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205812 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.90%
C000205812 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.50%
C000205811 [Member] | Supranational [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20%
C000205811 [Member] | Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10%
C000205811 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.70% [60]
C000205811 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.80% [60]
C000205811 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40% [60]
C000205811 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.50% [60]
C000205811 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.50% [60]
C000205811 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.50% [60]
C000205811 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.60% [60]
C000205811 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000205811 [Member] | ECUADOR  
Holdings [Line Items]  
Percent of Total Investments 1.00%
C000205811 [Member] | GERMANY  
Holdings [Line Items]  
Percent of Total Investments 2.90%
C000205811 [Member] | IRELAND  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000205811 [Member] | MEXICO  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205811 [Member] | UNITED ARAB EMIRATES  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000205811 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000205811 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 73.50%
C000205811 [Member] | TÜRKIYE  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205811 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.00%
C000205811 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.20%
C000205811 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 20.70%
C000205811 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000205811 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205811 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.90%
C000205811 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.50%
C000205814 [Member] | Supranational [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.20%
C000205814 [Member] | Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.10%
C000205814 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.70% [61]
C000205814 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.80% [61]
C000205814 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.40% [61]
C000205814 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.50% [61]
C000205814 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.50% [61]
C000205814 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.50% [61]
C000205814 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.60% [61]
C000205814 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 4.30%
C000205814 [Member] | ECUADOR  
Holdings [Line Items]  
Percent of Total Investments 1.00%
C000205814 [Member] | GERMANY  
Holdings [Line Items]  
Percent of Total Investments 2.90%
C000205814 [Member] | IRELAND  
Holdings [Line Items]  
Percent of Total Investments 2.00%
C000205814 [Member] | MEXICO  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205814 [Member] | UNITED ARAB EMIRATES  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000205814 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 0.70%
C000205814 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 73.50%
C000205814 [Member] | TÜRKIYE  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205814 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.00%
C000205814 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.20%
C000205814 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 20.70%
C000205814 [Member] | Preferred Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40%
C000205814 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205814 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.90%
C000205814 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.50%
C000205819 [Member] | Supranational [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.70%
C000205819 [Member] | Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205819 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.40% [62]
C000205819 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.40% [62]
C000205819 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [62]
C000205819 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.70% [62]
C000205819 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.10% [62]
C000205819 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.10% [62]
C000205819 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.40% [62]
C000205819 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 8.40%
C000205819 [Member] | UNITED ARAB EMIRATES  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205819 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000205819 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 66.80%
C000205819 [Member] | SWEDEN  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000205819 [Member] | NETHERLANDS  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205819 [Member] | KOREA, REPUBLIC OF  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000205819 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205819 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 3.30%
C000205819 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000205819 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.80%
C000205819 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 32.80%
C000205819 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90%
C000205819 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000205819 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 54.60%
C000205816 [Member] | Supranational [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.70%
C000205816 [Member] | Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205816 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.40% [63]
C000205816 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.40% [63]
C000205816 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [63]
C000205816 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.70% [63]
C000205816 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.10% [63]
C000205816 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.10% [63]
C000205816 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.40% [63]
C000205816 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 8.40%
C000205816 [Member] | UNITED ARAB EMIRATES  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205816 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000205816 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 66.80%
C000205816 [Member] | SWEDEN  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000205816 [Member] | NETHERLANDS  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205816 [Member] | KOREA, REPUBLIC OF  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000205816 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205816 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 3.30%
C000205816 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000205816 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.80%
C000205816 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 32.80%
C000205816 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90%
C000205816 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000205816 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 54.60%
C000205817 [Member] | Supranational [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.70%
C000205817 [Member] | Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205817 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.40% [64]
C000205817 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.40% [64]
C000205817 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [64]
C000205817 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.70% [64]
C000205817 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.10% [64]
C000205817 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.10% [64]
C000205817 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.40% [64]
C000205817 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 8.40%
C000205817 [Member] | UNITED ARAB EMIRATES  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205817 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000205817 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 66.80%
C000205817 [Member] | SWEDEN  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000205817 [Member] | NETHERLANDS  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205817 [Member] | KOREA, REPUBLIC OF  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000205817 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205817 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 3.30%
C000205817 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000205817 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.80%
C000205817 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 32.80%
C000205817 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90%
C000205817 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000205817 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 54.60%
C000205820 [Member] | Supranational [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.70%
C000205820 [Member] | Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205820 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.40% [65]
C000205820 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.40% [65]
C000205820 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [65]
C000205820 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.70% [65]
C000205820 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.10% [65]
C000205820 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.10% [65]
C000205820 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.40% [65]
C000205820 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 8.40%
C000205820 [Member] | UNITED ARAB EMIRATES  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205820 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000205820 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 66.80%
C000205820 [Member] | SWEDEN  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000205820 [Member] | NETHERLANDS  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205820 [Member] | KOREA, REPUBLIC OF  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000205820 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205820 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 3.30%
C000205820 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000205820 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.80%
C000205820 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 32.80%
C000205820 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90%
C000205820 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000205820 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 54.60%
C000205818 [Member] | Supranational [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.70%
C000205818 [Member] | Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.60%
C000205818 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.40% [66]
C000205818 [Member] | Moody's, Aaa Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.40% [66]
C000205818 [Member] | N A not applicable [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [66]
C000205818 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.70% [66]
C000205818 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.10% [66]
C000205818 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.10% [66]
C000205818 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.40% [66]
C000205818 [Member] | CANADA  
Holdings [Line Items]  
Percent of Total Investments 8.40%
C000205818 [Member] | UNITED ARAB EMIRATES  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205818 [Member] | UNITED KINGDOM  
Holdings [Line Items]  
Percent of Total Investments 1.10%
C000205818 [Member] | UNITED STATES  
Holdings [Line Items]  
Percent of Total Investments 66.80%
C000205818 [Member] | SWEDEN  
Holdings [Line Items]  
Percent of Total Investments 1.40%
C000205818 [Member] | NETHERLANDS  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205818 [Member] | KOREA, REPUBLIC OF  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000205818 [Member] | JAPAN  
Holdings [Line Items]  
Percent of Total Investments 0.30%
C000205818 [Member] | FRANCE  
Holdings [Line Items]  
Percent of Total Investments 3.30%
C000205818 [Member] | Investments Purchased with Collateral from Securities Lending [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000205818 [Member] | Structured Assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.80%
C000205818 [Member] | Government Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 32.80%
C000205818 [Member] | Repurchase Agreements [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90%
C000205818 [Member] | Bank Loan Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.80%
C000205818 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 54.60%
[1] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[2] Affiliated investment.
[3] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[4] Affiliated investment.
[5] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[6] Affiliated investment.
[7] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[8] Affiliated investment.
[9] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[10] Affiliated investment.
[11] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[12] Affiliated investment.
[13] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[14] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[15] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[16]  Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[17] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[18] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[19] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[20] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[21] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[22] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[23] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[24] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[25] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[26] Affiliated investment.
[27] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[28] Affiliated investment.
[29] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[30] Affiliated investment.
[31] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[32] Affiliated investment.
[33] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[34] Affiliated investment.
[35] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[36] Affiliated investment.
[37] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[38] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[39] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[40] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[41] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[42] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[43] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[44] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[45] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[46] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[47] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[48] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[49] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[50] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[51] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[52] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[53] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[54]  Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[55] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[56] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[57] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[58] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[59] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[60] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[61] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[62] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[63] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[64] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[65] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.
[66] Credit quality ratings are based on the Bloomberg Barclays methodology, which uses the median rating of those compiled by the Moody’s, Standard & Poor’s and Fitch ratings agencies. If ratings are available from only two of these agencies, the lower rating is used. When only one rating is available, that one is used. These ratings are subject to change without notice.