v3.25.2
Shareholder Report, Line Graph (Details) - USD ($)
 12 Months Ended 24 Months Ended 36 Months Ended 48 Months Ended 60 Months Ended 72 Months Ended 84 Months Ended 96 Months Ended 108 Months Ended 120 Months Ended
May 31, 2015
May 31, 2025
May 31, 2016
May 31, 2017
May 31, 2018
May 31, 2019
May 31, 2020
May 31, 2021
May 31, 2022
May 31, 2023
May 31, 2024
May 31, 2025
C000001498 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value $ 9,584   $ 10,189 $ 10,299 $ 10,441 $ 10,999 $ 11,322 $ 11,959 $ 11,041 $ 10,942 $ 11,331 $ 11,388
C000001501 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,651 10,784 10,950 11,566 11,919 12,618 11,671 11,591 12,025 12,107
C000001497 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,668 10,693 10,919 11,684 12,062 12,702 11,961 11,714 12,205 12,210
C000001490 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,577   10,109 10,192 10,297 10,807 11,232 11,736 10,990 10,875 11,235 11,332
C000001493 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,576 10,686 10,811 11,369 11,842 12,409 11,640 11,535 11,950 12,066
C000001494 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,583   10,204 10,203 10,391 11,110 11,446 12,026 11,302 11,046 11,488 11,472
C000001489 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,582 10,780 10,956 11,520 11,752 12,566 11,679 11,560 11,988 12,142
C000001486 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,580   10,115 10,282 10,436 10,948 11,144 11,893 11,029 10,906 11,274 11,410
C000001474 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,580   10,175 10,261 10,419 11,010 11,357 11,976 11,082 10,968 11,361 11,429
C000001477 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,637 10,749 10,938 11,583 11,974 12,640 11,724 11,627 12,067 12,162
C000001478 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,579   10,231 10,309 10,509 11,122 11,569 12,141 11,259 11,189 11,544 11,645
C000001481 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,709 10,809 11,048 11,712 12,197 12,827 11,920 11,867 12,267 12,396
S And P Municipal Bond Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Index                    
Accumulated Value 10,000   10,571 10,738 10,873 11,532 11,979 12,542 11,793 11,815 12,155 12,452
Lipper Virginia Municipal Debt Funds Classification Average [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Lipper Virginia Municipal Debt Funds Classification Average                    
S And P Municipal Bond Virginia Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Virginia Index                    
Accumulated Value 10,000   10,567 10,759 10,835 11,443 11,990 12,373 11,673 11,668 11,961 12,268
S And P Municipal Bond Pennsylvania Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Pennsylvania Index                    
Accumulated Value 10,000   10,583 10,756 10,921 11,631 12,094 12,691 11,926 11,903 12,248 12,589
Lipper Pennsylvania Municipal Debt Funds Classification Average [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Lipper Pennsylvania Municipal Debt Funds Classification Average                    
S And P Municipal Bond New Mexico Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond New Mexico Index                    
Accumulated Value 10,000   10,427 10,586 10,629 11,157 11,621 11,954 11,385 11,390 11,638 12,087
Lipper Other States Municipal Debt Funds Classification Average [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Lipper Other States Municipal Debt Funds Classification Average                    
S And P Municipal Bond Maryland Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Maryland Index                    
Accumulated Value 10,000   10,469 10,633 10,681 11,270 11,756 12,125 11,427 11,453 11,683 12,049
Lipper Maryland Municipal Debt Funds Classification Average [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Lipper Maryland Municipal Debt Funds Classification Average                    
S And P Municipal Bond Colorado Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Colorado Index                    
Accumulated Value 10,000   10,650 10,837 11,045 11,759 12,201 12,906 12,098 12,126 12,548 12,937
S And P Municipal Bond Arizona Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Arizona Index                    
Accumulated Value $ 10,000   $ 10,546 $ 10,697 $ 10,803 $ 11,424 $ 11,832 $ 12,370 $ 11,693 $ 11,655 $ 12,039 $ 12,365