v3.26.1
Shareholder Report, Holdings (Details)
May 31, 2026
C000001376 [Member] | Medical [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.60%
C000001376 [Member] | Transportation Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
C000001376 [Member] | Education [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.10%
C000001376 [Member] | Airport [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.00%
C000001376 [Member] | Housing [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
C000001376 [Member] | Nursing Homes [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
C000001376 [Member] | Power [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
C000001376 [Member] | Tobacco Settlement [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.70%
C000001376 [Member] | Development [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
C000001376 [Member] | School District [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
C000001376 [Member] | Water And Sewer [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000001376 [Member] | General Obligation [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 10.20%
C000001376 [Member] | Net Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.10%
C000001378 [Member] | Medical [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.60%
C000001378 [Member] | Transportation Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
C000001378 [Member] | Education [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.10%
C000001378 [Member] | Airport [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.00%
C000001378 [Member] | Housing [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
C000001378 [Member] | Nursing Homes [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
C000001378 [Member] | Power [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
C000001378 [Member] | Tobacco Settlement [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.70%
C000001378 [Member] | Development [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
C000001378 [Member] | School District [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
C000001378 [Member] | Water And Sewer [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000001378 [Member] | General Obligation [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 10.20%
C000001378 [Member] | Net Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.10%
C000000023 [Member] | Medical [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.60%
C000000023 [Member] | Transportation Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
C000000023 [Member] | Education [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.10%
C000000023 [Member] | Airport [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.00%
C000000023 [Member] | Housing [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
C000000023 [Member] | Nursing Homes [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
C000000023 [Member] | Power [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
C000000023 [Member] | Tobacco Settlement [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.70%
C000000023 [Member] | Development [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
C000000023 [Member] | School District [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
C000000023 [Member] | Water And Sewer [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000000023 [Member] | General Obligation [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 10.20%
C000000023 [Member] | Net Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.10%
C000130450 [Member] | Medical [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.60%
C000130450 [Member] | Transportation Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
C000130450 [Member] | Education [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.10%
C000130450 [Member] | Airport [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.00%
C000130450 [Member] | Housing [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
C000130450 [Member] | Nursing Homes [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
C000130450 [Member] | Power [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
C000130450 [Member] | Tobacco Settlement [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.70%
C000130450 [Member] | Development [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
C000130450 [Member] | School District [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
C000130450 [Member] | Water And Sewer [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000130450 [Member] | General Obligation [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 10.20%
C000130450 [Member] | Net Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.10%
C000073387 [Member] | Medical [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 14.60%
C000073387 [Member] | Transportation Sector [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
C000073387 [Member] | Education [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.10%
C000073387 [Member] | Airport [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.00%
C000073387 [Member] | Housing [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
C000073387 [Member] | Nursing Homes [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
C000073387 [Member] | Power [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
C000073387 [Member] | Tobacco Settlement [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.70%
C000073387 [Member] | Development [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
C000073387 [Member] | School District [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
C000073387 [Member] | Water And Sewer [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000073387 [Member] | General Obligation [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 10.20%
C000073387 [Member] | Net Other Assets and Liabilities [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 17.10%