Shareholder Report, Holdings (Details)
|
May 31, 2026 |
| C000001477 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
10.70%
|
[1] |
| C000001477 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
2.90%
|
[1] |
| C000001477 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
5.80%
|
[1] |
| C000001477 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
12.50%
|
[1] |
| C000001477 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
59.80%
|
[1] |
| C000001477 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
8.30%
|
[1] |
| C000001477 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000137693 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
10.70%
|
[2] |
| C000137693 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
2.90%
|
[2] |
| C000137693 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
5.80%
|
[2] |
| C000137693 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
12.50%
|
[2] |
| C000137693 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
59.80%
|
[2] |
| C000137693 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
8.30%
|
[2] |
| C000137693 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001474 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
10.70%
|
[3] |
| C000001474 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
2.90%
|
[3] |
| C000001474 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
5.80%
|
[3] |
| C000001474 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
12.50%
|
[3] |
| C000001474 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
59.80%
|
[3] |
| C000001474 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
8.30%
|
[3] |
| C000001474 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001478 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
11.90%
|
[4] |
| C000001478 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
2.30%
|
[4] |
| C000001478 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
6.20%
|
[4] |
| C000001478 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
17.30%
|
[4] |
| C000001478 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
57.40%
|
[4] |
| C000001478 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.90%
|
[4] |
| C000001478 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000137694 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
11.90%
|
[5] |
| C000137694 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
2.30%
|
[5] |
| C000137694 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
6.20%
|
[5] |
| C000137694 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
17.30%
|
[5] |
| C000137694 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
57.40%
|
[5] |
| C000137694 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.90%
|
[5] |
| C000137694 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001481 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
11.90%
|
[6] |
| C000001481 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
2.30%
|
[6] |
| C000001481 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
6.20%
|
[6] |
| C000001481 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
17.30%
|
[6] |
| C000001481 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
57.40%
|
[6] |
| C000001481 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.90%
|
[6] |
| C000001481 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001489 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
16.40%
|
[7] |
| C000001489 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.60%
|
[7] |
| C000001489 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
13.70%
|
[7] |
| C000001489 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
23.40%
|
[7] |
| C000001489 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
29.80%
|
[7] |
| C000001489 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
12.10%
|
[7] |
| C000001489 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000137695 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
16.40%
|
[8] |
| C000137695 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.60%
|
[8] |
| C000137695 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
13.70%
|
[8] |
| C000137695 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
23.40%
|
[8] |
| C000137695 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
29.80%
|
[8] |
| C000137695 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
12.10%
|
[8] |
| C000137695 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001486 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
16.40%
|
[9] |
| C000001486 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.60%
|
[9] |
| C000001486 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
13.70%
|
[9] |
| C000001486 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
23.40%
|
[9] |
| C000001486 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
29.80%
|
[9] |
| C000001486 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
12.10%
|
[9] |
| C000001486 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001490 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
16.20%
|
[10] |
| C000001490 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
5.30%
|
[10] |
| C000001490 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.70%
|
[10] |
| C000001490 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
57.80%
|
[10] |
| C000001490 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
16.00%
|
[10] |
| C000001490 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000137696 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
16.20%
|
[11] |
| C000137696 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
5.30%
|
[11] |
| C000137696 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.70%
|
[11] |
| C000137696 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
57.80%
|
[11] |
| C000137696 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
16.00%
|
[11] |
| C000137696 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001493 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
16.20%
|
[12] |
| C000001493 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
5.30%
|
[12] |
| C000001493 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.70%
|
[12] |
| C000001493 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
57.80%
|
[12] |
| C000001493 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
16.00%
|
[12] |
| C000001493 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001497 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
9.00%
|
[13] |
| C000001497 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
2.90%
|
[13] |
| C000001497 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
9.60%
|
[13] |
| C000001497 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
18.10%
|
[13] |
| C000001497 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
60.00%
|
[13] |
| C000001497 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
0.40%
|
[13] |
| C000001497 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001497 [Member] | Variable Rate Senior Loan Interests [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
0.00%
|
|
| C000137697 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
9.00%
|
[14] |
| C000137697 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
2.90%
|
[14] |
| C000137697 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
9.60%
|
[14] |
| C000137697 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
18.10%
|
[14] |
| C000137697 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
60.00%
|
[14] |
| C000137697 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
0.40%
|
[14] |
| C000137697 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000137697 [Member] | Variable Rate Senior Loan Interests [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
0.00%
|
|
| C000001494 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
9.00%
|
[15] |
| C000001494 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
2.90%
|
[15] |
| C000001494 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
9.60%
|
[15] |
| C000001494 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
18.10%
|
[15] |
| C000001494 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
60.00%
|
[15] |
| C000001494 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
0.40%
|
[15] |
| C000001494 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001494 [Member] | Variable Rate Senior Loan Interests [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
0.00%
|
|
| C000001498 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
14.90%
|
[16] |
| C000001498 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.90%
|
[16] |
| C000001498 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
11.30%
|
[16] |
| C000001498 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
9.80%
|
[16] |
| C000001498 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
47.30%
|
[16] |
| C000001498 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
11.80%
|
[16] |
| C000001498 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000137698 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
14.90%
|
[17] |
| C000137698 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.90%
|
[17] |
| C000137698 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
11.30%
|
[17] |
| C000137698 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
9.80%
|
[17] |
| C000137698 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
47.30%
|
[17] |
| C000137698 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
11.80%
|
[17] |
| C000137698 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
| C000001501 [Member] | N R not rated [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
14.90%
|
[18] |
| C000001501 [Member] | BB or Lower [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
4.90%
|
[18] |
| C000001501 [Member] | Standard & Poor's, BBB Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
11.30%
|
[18] |
| C000001501 [Member] | Standard & Poor's, A Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
9.80%
|
[18] |
| C000001501 [Member] | Standard & Poor's, AA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
47.30%
|
[18] |
| C000001501 [Member] | Standard & Poor's, AAA Rating [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
11.80%
|
[18] |
| C000001501 [Member] | Municipal Bonds [Member] |
|
|
| Holdings [Line Items] |
|
|
| Percent of Total Investments |
100.00%
|
|
|
|