v3.25.2
Shareholder Report, Holdings (Details)
May 31, 2025
C000001556 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.40% [1]
C000001556 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 64.80% [1]
C000001556 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.20% [1]
C000001556 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.50% [1]
C000001556 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.10% [1]
C000001556 [Member] | Municipal Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00%
C000137685 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.40% [2]
C000137685 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 64.80% [2]
C000137685 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.20% [2]
C000137685 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.50% [2]
C000137685 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.10% [2]
C000137685 [Member] | Municipal Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00%
C000001559 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.40% [3]
C000001559 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 64.80% [3]
C000001559 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.20% [3]
C000001559 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.50% [3]
C000001559 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.10% [3]
C000001559 [Member] | Municipal Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00%
C000001551 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.30% [4]
C000001551 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 45.70% [4]
C000001551 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.80% [4]
C000001551 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.60% [4]
C000001551 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.60% [4]
C000001551 [Member] | Municipal Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00%
C000001548 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.30% [5]
C000001548 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 45.70% [5]
C000001548 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.80% [5]
C000001548 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.60% [5]
C000001548 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.60% [5]
C000001548 [Member] | Municipal Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00%
C000137683 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.30% [6]
C000137683 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 45.70% [6]
C000137683 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.80% [6]
C000137683 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.60% [6]
C000137683 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.60% [6]
C000137683 [Member] | Municipal Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00%
C000001552 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.00% [7]
C000001552 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60% [7]
C000001552 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 32.80% [7]
C000001552 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.40% [7]
C000001552 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00% [7]
C000001552 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.20% [7]
C000001552 [Member] | Municipal Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00%
C000137684 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.00% [8]
C000137684 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60% [8]
C000137684 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 32.80% [8]
C000137684 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.40% [8]
C000137684 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00% [8]
C000137684 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.20% [8]
C000137684 [Member] | Municipal Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00%
C000001555 [Member] | N R not rated [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.00% [9]
C000001555 [Member] | BB or Lower [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.60% [9]
C000001555 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 32.80% [9]
C000001555 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.40% [9]
C000001555 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.00% [9]
C000001555 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.20% [9]
C000001555 [Member] | Municipal Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00%
[1] The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
[2] The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
[3] The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
[4] The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
[5] The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
[6] The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
[7] The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
[8] The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.
[9] The ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A, and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national ratings agencies.