Shareholder Report, Holdings (Details)	Nov. 30, 2025
C000015135 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	14.10%	[1]
C000015135 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	4.70%	[1]
C000015135 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	7.80%	[1]
C000015135 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	15.20%	[1]
C000015135 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	36.20%	[1]
C000015135 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	22.00%	[1]
C000015135 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000137678 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	14.10%	[2]
C000137678 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	4.70%	[2]
C000137678 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	7.80%	[2]
C000137678 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	15.20%	[2]
C000137678 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	36.20%	[2]
C000137678 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	22.00%	[2]
C000137678 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000015134 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	14.10%	[3]
C000015134 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	4.70%	[3]
C000015134 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	7.80%	[3]
C000015134 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	15.20%	[3]
C000015134 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	36.20%	[3]
C000015134 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	22.00%	[3]
C000015134 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000015136 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	14.00%	[4]
C000015136 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	6.00%	[4]
C000015136 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	4.40%	[4]
C000015136 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	23.60%	[4]
C000015136 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	34.50%	[4]
C000015136 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	17.50%	[4]
C000015136 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000137679 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	14.00%	[5]
C000137679 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	6.00%	[5]
C000137679 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	4.40%	[5]
C000137679 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	23.60%	[5]
C000137679 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	34.50%	[5]
C000137679 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	17.50%	[5]
C000137679 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000015138 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	14.00%	[6]
C000015138 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	6.00%	[6]
C000015138 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	4.40%	[6]
C000015138 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	23.60%	[6]
C000015138 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	34.50%	[6]
C000015138 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	17.50%	[6]
C000015138 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000015141 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	8.10%	[7]
C000015141 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	1.20%	[7]
C000015141 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	3.50%	[7]
C000015141 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	19.00%	[7]
C000015141 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	65.90%	[7]
C000015141 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	2.30%	[7]
C000015141 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000137680 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	8.10%	[8]
C000137680 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	1.20%	[8]
C000137680 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	3.50%	[8]
C000137680 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	19.00%	[8]
C000137680 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	65.90%	[8]
C000137680 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	2.30%	[8]
C000137680 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000015139 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	8.10%	[9]
C000015139 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	1.20%	[9]
C000015139 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	3.50%	[9]
C000015139 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	19.00%	[9]
C000015139 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	65.90%	[9]
C000015139 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	2.30%	[9]
C000015139 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000015145 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	6.30%	[10]
C000015145 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	1.30%	[10]
C000015145 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	8.30%	[10]
C000015145 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	13.20%	[10]
C000015145 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	65.70%	[10]
C000015145 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	5.20%	[10]
C000015145 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000137681 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	6.30%	[11]
C000137681 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	1.30%	[11]
C000137681 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	8.30%	[11]
C000137681 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	13.20%	[11]
C000137681 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	65.70%	[11]
C000137681 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	5.20%	[11]
C000137681 [Member] | Municipal Bonds [Member]
Holdings [Line Items]
Percent of Total Investments	100.00%
C000015146 [Member] | N R not rated [Member]
Holdings [Line Items]
Percent of Total Investments	6.30%	[12]
C000015146 [Member] | BB or Lower [Member]
Holdings [Line Items]
Percent of Total Investments	1.30%	[12]
C000015146 [Member] | Standard & Poor's, BBB Rating [Member]
Holdings [Line Items]
Percent of Total Investments	8.30%	[12]
C000015146 [Member] | Standard & Poor's, A Rating [Member]
Holdings [Line Items]
Percent of Total Investments	13.20%	[12]
C000015146 [Member] | Standard & Poor's, AA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	65.70%	[12]
C000015146 [Member] | Standard & Poor's, AAA Rating [Member]
Holdings [Line Items]
Percent of Total Investments	5.20%	[12]
C000015146 [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.

[10] 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.

[11] 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.

[12] 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.