v3.25.2
Shareholder Report, Holdings (Details)
May 31, 2025
C000017685 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.30%
C000017685 [Member] | Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000088012 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.30%
C000088012 [Member] | Exchange-Traded Fund [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000189766 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.30%
C000189766 [Member] | Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000017686 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.30%
C000017686 [Member] | Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000017688 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.30%
C000017688 [Member] | Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000017689 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.50%
C000017689 [Member] | Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000017689 [Member] | Exchange-Traded Fund [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
C000017689 [Member] | Short-Term Investment [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000017691 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.50%
C000017691 [Member] | Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000017691 [Member] | Exchange-Traded Fund [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
C000017691 [Member] | Short-Term Investment [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000189767 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.50%
C000189767 [Member] | Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000189767 [Member] | Exchange-Traded Fund [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
C000189767 [Member] | Short-Term Investment [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000088013 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.50%
C000088013 [Member] | Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000088013 [Member] | Exchange-Traded Fund [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
C000088013 [Member] | Short-Term Investment [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000088014 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.50%
C000088014 [Member] | Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000088014 [Member] | Exchange-Traded Fund [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
C000088014 [Member] | Short-Term Investment [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000017692 [Member] | Municipal Securities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 99.20%
C000017692 [Member] | Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%