v3.25.2
Shareholder Report, Holdings (Details)
Jun. 30, 2025
C000032726 [Member] | A [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.25%
C000032726 [Member] | Aaa AAA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.02%
C000032726 [Member] | Aa AA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 95.73%
C000032726 [Member] | Prerefunded [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.51%
C000032726 [Member] | Miscellaneous Public Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.06%
C000032726 [Member] | Other Assets Less Liabilities [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.16%
C000032726 [Member] | Hospital and Healthcare Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.53%
C000032726 [Member] | School Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 26.27%
C000032726 [Member] | Public Facilities Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.63%
C000032726 [Member] | University Consolidated Education and Building Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.92%
C000032726 [Member] | Municipal Utility Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.87%
C000032726 [Member] | State and Local Mortgage Housing Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.13%
C000032726 [Member] | Refunding [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.92%
C000032727 [Member] | A [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 8.68%
C000032727 [Member] | Aaa AAA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.87%
C000032727 [Member] | Aa AA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 86.45%
C000032727 [Member] | Airport Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.23%
C000032727 [Member] | Miscellaneous Public Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 28.95%
C000032727 [Member] | Other Assets Less Liabilities [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.54%
C000032727 [Member] | Hospital and Healthcare Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.02%
C000032727 [Member] | School Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 31.80%
C000032727 [Member] | Turnpikes Toll Road Highway Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.28%
C000032727 [Member] | Public Facilities Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.48%
C000032727 [Member] | University Consolidated Education and Building Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.65%
C000032727 [Member] | Municipal Utility Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.37%
C000032727 [Member] | State and Local Mortgage Housing Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.84%
C000032727 [Member] | Refunding [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.39%
C000032727 [Member] | Ad Valorem Property [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.45%
C000032729 [Member] | A [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.87%
C000032729 [Member] | Aaa AAA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000032729 [Member] | Aa AA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 97.13%
C000032729 [Member] | Miscellaneous Public Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.84%
C000032729 [Member] | Hospital and Healthcare Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.68%
C000032729 [Member] | School Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.09%
C000032729 [Member] | Public Facilities Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 18.64%
C000032729 [Member] | University Consolidated Education and Building Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.98%
C000032729 [Member] | State and Local Mortgage Housing Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 13.49%
C000032729 [Member] | Lease Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.92%
C000032729 [Member] | Liabilities in excess of assets [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.36%
C000032730 [Member] | A [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 13.55%
C000032730 [Member] | Not Rated [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.59%
C000032730 [Member] | Aaa AAA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 4.92%
C000032730 [Member] | Aa AA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 79.94%
C000032730 [Member] | Prerefunded [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30%
C000032730 [Member] | Airport Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.35%
C000032730 [Member] | Miscellaneous Public Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.17%
C000032730 [Member] | Other Assets Less Liabilities [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.03%
C000032730 [Member] | Hospital and Healthcare Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.58%
C000032730 [Member] | School Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.24%
C000032730 [Member] | Turnpikes Toll Road Highway Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.34%
C000032730 [Member] | Public Facilities Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.67%
C000032730 [Member] | University Consolidated Education and Building Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.39%
C000032730 [Member] | Municipal Utility Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 20.17%
C000032730 [Member] | State and Local Mortgage Housing Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.65%
C000032730 [Member] | Lease Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10%
C000032730 [Member] | Refunding [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.01%
C000032732 [Member] | A [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 20.47%
C000032732 [Member] | Aaa AAA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.86%
C000032732 [Member] | Aa AA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 77.67%
C000032732 [Member] | Prerefunded [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.30%
C000032732 [Member] | Airport Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.89%
C000032732 [Member] | Miscellaneous Public Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.40%
C000032732 [Member] | Other Assets Less Liabilities [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.88%
C000032732 [Member] | Hospital and Healthcare Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.19%
C000032732 [Member] | School Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.75%
C000032732 [Member] | Public Facilities Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 8.60%
C000032732 [Member] | University Consolidated Education and Building Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.20%
C000032732 [Member] | Municipal Utility Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 49.06%
C000032732 [Member] | State and Local Mortgage Housing Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.41%
C000032732 [Member] | Refunding [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.32%
C000032734 [Member] | Aa1 [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00%
C000032734 [Member] | Other Assets Less Liabilities [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.29%
C000032734 [Member] | Federal Home Loan Bank [Member]  
Holdings [Line Items]  
Percent of Total Investments 79.50%
C000032734 [Member] | Federal Home Loan Mortgage Corporation [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.07%
C000032734 [Member] | Federal Farm Credit [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.14%
C000093320 [Member] | A [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 3.17%
C000093320 [Member] | Not Rated [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.77%
C000093320 [Member] | Aaa AAA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 12.57%
C000093320 [Member] | Aa AA [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 83.49%
C000093320 [Member] | Prerefunded [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.73%
C000093320 [Member] | Airport Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.54%
C000093320 [Member] | Miscellaneous Public Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.68%
C000093320 [Member] | Other Assets Less Liabilities [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.92%
C000093320 [Member] | Hospital and Healthcare Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000093320 [Member] | School Improvement [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.20%
C000093320 [Member] | Marina Port Authority Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 6.88%
C000093320 [Member] | Turnpikes Toll Road Highway Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.87%
C000093320 [Member] | Public Facilities Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 9.98%
C000093320 [Member] | University Consolidated Education and Building Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.59%
C000093320 [Member] | Municipal Utility Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.26%
C000093320 [Member] | State and Local Mortgage Housing Revenue [Member]  
Holdings [Line Items]  
Percent of Total Investments 22.45%