v3.25.1
Shareholder Report, Holdings (Details)
Mar. 31, 2025
C000024774 [Member] | Pre refunded Escrowed to Maturity [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
C000024774 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
C000024774 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 82.70%
C000024774 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.80%
C000024774 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000024774 [Member] | Standard & Poor's, BB Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000024774 [Member] | Cash [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000024775 [Member] | Pre refunded Escrowed to Maturity [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
C000024775 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
C000024775 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 82.70%
C000024775 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.80%
C000024775 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000024775 [Member] | Standard & Poor's, BB Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000024775 [Member] | Cash [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000188793 [Member] | Pre refunded Escrowed to Maturity [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
C000188793 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
C000188793 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 82.70%
C000188793 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.80%
C000188793 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000188793 [Member] | Standard & Poor's, BB Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000188793 [Member] | Cash [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
C000024777 [Member] | Pre refunded Escrowed to Maturity [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
C000024777 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
C000024777 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 82.70%
C000024777 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 5.80%
C000024777 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
C000024777 [Member] | Standard & Poor's, BB Rating [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
C000024777 [Member] | Cash [Member]  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%