Shareholder Report, Holdings (Details)
|
May 31, 2025 |
| C000001854 [Member] | US Government Debt Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000001854 [Member] | Moody's, Aaa Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.90%
|
| C000001854 [Member] | US Government Corporations and Agencies Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000001854 [Member] | Standard & Poor's, AA Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.50%
|
| C000001854 [Member] | Standard & Poor's, A Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
6.30%
|
| C000001854 [Member] | Standard & Poor's, BBB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
20.70%
|
| C000001854 [Member] | Standard & Poor's, BB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
7.00%
|
| C000001854 [Member] | Standard & Poor's, B Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.50%
|
| C000001854 [Member] | Mortgage Backed Security Issued by US Government Sponsored Enterprise Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000001854 [Member] | Not rated [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.30%
|
| C000001854 [Member] | Short term investments and other Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000001854 [Member] | Corporate Bond Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
35.50%
|
| C000001854 [Member] | US Government Corporations and Agencies Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000001854 [Member] | US Government Debt Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000001854 [Member] | Asset-Backed Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.70%
|
| C000001854 [Member] | Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000001854 [Member] | Mortgage-Backed Securities, Issued by Private Enterprises [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.60%
|
| C000001854 [Member] | Term loans [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.30%
|
| C000001854 [Member] | Preferred securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.10%
|
| C000001854 [Member] | Short term investments and other [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000001856 [Member] | US Government Debt Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000001856 [Member] | Moody's, Aaa Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.90%
|
| C000001856 [Member] | US Government Corporations and Agencies Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000001856 [Member] | Standard & Poor's, AA Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.50%
|
| C000001856 [Member] | Standard & Poor's, A Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
6.30%
|
| C000001856 [Member] | Standard & Poor's, BBB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
20.70%
|
| C000001856 [Member] | Standard & Poor's, BB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
7.00%
|
| C000001856 [Member] | Standard & Poor's, B Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.50%
|
| C000001856 [Member] | Mortgage Backed Security Issued by US Government Sponsored Enterprise Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000001856 [Member] | Not rated [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.30%
|
| C000001856 [Member] | Short term investments and other Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000001856 [Member] | Corporate Bond Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
35.50%
|
| C000001856 [Member] | US Government Corporations and Agencies Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000001856 [Member] | US Government Debt Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000001856 [Member] | Asset-Backed Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.70%
|
| C000001856 [Member] | Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000001856 [Member] | Mortgage-Backed Securities, Issued by Private Enterprises [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.60%
|
| C000001856 [Member] | Term loans [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.30%
|
| C000001856 [Member] | Preferred securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.10%
|
| C000001856 [Member] | Short term investments and other [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000001857 [Member] | US Government Debt Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000001857 [Member] | Moody's, Aaa Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.90%
|
| C000001857 [Member] | US Government Corporations and Agencies Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000001857 [Member] | Standard & Poor's, AA Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.50%
|
| C000001857 [Member] | Standard & Poor's, A Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
6.30%
|
| C000001857 [Member] | Standard & Poor's, BBB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
20.70%
|
| C000001857 [Member] | Standard & Poor's, BB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
7.00%
|
| C000001857 [Member] | Standard & Poor's, B Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.50%
|
| C000001857 [Member] | Mortgage Backed Security Issued by US Government Sponsored Enterprise Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000001857 [Member] | Not rated [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.30%
|
| C000001857 [Member] | Short term investments and other Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000001857 [Member] | Corporate Bond Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
35.50%
|
| C000001857 [Member] | US Government Corporations and Agencies Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000001857 [Member] | US Government Debt Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000001857 [Member] | Asset-Backed Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.70%
|
| C000001857 [Member] | Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000001857 [Member] | Mortgage-Backed Securities, Issued by Private Enterprises [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.60%
|
| C000001857 [Member] | Term loans [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.30%
|
| C000001857 [Member] | Preferred securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.10%
|
| C000001857 [Member] | Short term investments and other [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000153977 [Member] | US Government Debt Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000153977 [Member] | Moody's, Aaa Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.90%
|
| C000153977 [Member] | US Government Corporations and Agencies Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000153977 [Member] | Standard & Poor's, AA Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.50%
|
| C000153977 [Member] | Standard & Poor's, A Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
6.30%
|
| C000153977 [Member] | Standard & Poor's, BBB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
20.70%
|
| C000153977 [Member] | Standard & Poor's, BB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
7.00%
|
| C000153977 [Member] | Standard & Poor's, B Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.50%
|
| C000153977 [Member] | Mortgage Backed Security Issued by US Government Sponsored Enterprise Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000153977 [Member] | Not rated [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.30%
|
| C000153977 [Member] | Short term investments and other Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000153977 [Member] | Corporate Bond Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
35.50%
|
| C000153977 [Member] | US Government Corporations and Agencies Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000153977 [Member] | US Government Debt Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000153977 [Member] | Asset-Backed Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.70%
|
| C000153977 [Member] | Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000153977 [Member] | Mortgage-Backed Securities, Issued by Private Enterprises [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.60%
|
| C000153977 [Member] | Term loans [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.30%
|
| C000153977 [Member] | Preferred securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.10%
|
| C000153977 [Member] | Short term investments and other [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000113488 [Member] | US Government Debt Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000113488 [Member] | Moody's, Aaa Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.90%
|
| C000113488 [Member] | US Government Corporations and Agencies Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000113488 [Member] | Standard & Poor's, AA Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.50%
|
| C000113488 [Member] | Standard & Poor's, A Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
6.30%
|
| C000113488 [Member] | Standard & Poor's, BBB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
20.70%
|
| C000113488 [Member] | Standard & Poor's, BB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
7.00%
|
| C000113488 [Member] | Standard & Poor's, B Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.50%
|
| C000113488 [Member] | Mortgage Backed Security Issued by US Government Sponsored Enterprise Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000113488 [Member] | Not rated [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.30%
|
| C000113488 [Member] | Short term investments and other Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000113488 [Member] | Corporate Bond Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
35.50%
|
| C000113488 [Member] | US Government Corporations and Agencies Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000113488 [Member] | US Government Debt Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000113488 [Member] | Asset-Backed Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.70%
|
| C000113488 [Member] | Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000113488 [Member] | Mortgage-Backed Securities, Issued by Private Enterprises [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.60%
|
| C000113488 [Member] | Term loans [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.30%
|
| C000113488 [Member] | Preferred securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.10%
|
| C000113488 [Member] | Short term investments and other [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000153978 [Member] | US Government Debt Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000153978 [Member] | Moody's, Aaa Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.90%
|
| C000153978 [Member] | US Government Corporations and Agencies Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000153978 [Member] | Standard & Poor's, AA Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.50%
|
| C000153978 [Member] | Standard & Poor's, A Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
6.30%
|
| C000153978 [Member] | Standard & Poor's, BBB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
20.70%
|
| C000153978 [Member] | Standard & Poor's, BB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
7.00%
|
| C000153978 [Member] | Standard & Poor's, B Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.50%
|
| C000153978 [Member] | Mortgage Backed Security Issued by US Government Sponsored Enterprise Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000153978 [Member] | Not rated [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.30%
|
| C000153978 [Member] | Short term investments and other Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000153978 [Member] | Corporate Bond Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
35.50%
|
| C000153978 [Member] | US Government Corporations and Agencies Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000153978 [Member] | US Government Debt Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000153978 [Member] | Asset-Backed Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.70%
|
| C000153978 [Member] | Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000153978 [Member] | Mortgage-Backed Securities, Issued by Private Enterprises [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.60%
|
| C000153978 [Member] | Term loans [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.30%
|
| C000153978 [Member] | Preferred securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.10%
|
| C000153978 [Member] | Short term investments and other [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000106442 [Member] | US Government Debt Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000106442 [Member] | Moody's, Aaa Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.90%
|
| C000106442 [Member] | US Government Corporations and Agencies Securities Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000106442 [Member] | Standard & Poor's, AA Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.50%
|
| C000106442 [Member] | Standard & Poor's, A Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
6.30%
|
| C000106442 [Member] | Standard & Poor's, BBB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
20.70%
|
| C000106442 [Member] | Standard & Poor's, BB Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
7.00%
|
| C000106442 [Member] | Standard & Poor's, B Rating [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.50%
|
| C000106442 [Member] | Mortgage Backed Security Issued by US Government Sponsored Enterprise Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000106442 [Member] | Not rated [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.30%
|
| C000106442 [Member] | Short term investments and other Quality [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|
| C000106442 [Member] | Corporate Bond Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
35.50%
|
| C000106442 [Member] | US Government Corporations and Agencies Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
36.10%
|
| C000106442 [Member] | US Government Debt Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
18.80%
|
| C000106442 [Member] | Asset-Backed Securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
4.70%
|
| C000106442 [Member] | Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
1.00%
|
| C000106442 [Member] | Mortgage-Backed Securities, Issued by Private Enterprises [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
2.60%
|
| C000106442 [Member] | Term loans [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.30%
|
| C000106442 [Member] | Preferred securities [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.10%
|
| C000106442 [Member] | Short term investments and other [Member] |
|
| Holdings [Line Items] |
|
| Percent of Net Asset Value |
0.90%
|