v3.26.1
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, 2016
May 31, 2026
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
May 31, 2026
C000001477 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value $ 10,000   $ 10,105 $ 10,284 $ 10,890 $ 11,257 $ 11,883 $ 11,022 $ 10,931 $ 11,344 $ 11,434 $ 12,265
C000001474 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,583   9,664 9,813 10,369 10,696 11,279 10,437 10,330 10,700 10,764 11,531
C000001478 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,583   9,656 9,843 10,418 10,836 11,372 10,546 10,480 10,813 10,908 11,625
C000001481 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,093 10,316 10,937 11,389 11,977 11,131 11,082 11,454 11,575 12,360
C000001489 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,187 10,354 10,886 11,105 11,875 11,036 10,924 11,328 11,474 12,364
C000001486 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,579   9,737 9,883 10,367 10,553 11,262 10,444 10,328 10,676 10,805 11,621
C000001490 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,578   9,656 9,755 10,238 10,641 11,119 10,412 10,303 10,644 10,736 11,526
C000001493 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,104 10,221 10,750 11,196 11,733 11,006 10,906 11,299 11,408 12,275
C000001497 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,024 10,236 10,953 11,307 11,907 11,213 10,981 11,441 11,446 12,399
C000001494 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,577   9,576 9,753 10,427 10,742 11,287 10,608 10,367 10,782 10,767 11,642
C000001498 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,579   9,683 9,816 10,340 10,644 11,243 10,379 10,287 10,652 10,706 11,475
C000001501 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,125 10,281 10,859 11,191 11,846 10,957 10,882 11,290 11,367 12,218
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   10,158 10,285 10,909 11,331 11,864 11,156 11,177 11,498 11,779 12,554
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 Arizona Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Arizona Index                    
Accumulated Value 10,000   10,143 10,243 10,832 11,219 11,729 11,087 11,051 11,416 11,725 12,488
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   10,176 10,371 11,042 11,457 12,119 11,359 11,386 11,782 12,147 13,034
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 Maryland Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Maryland Index                    
Accumulated Value 10,000   10,156 10,202 10,765 11,229 11,582 10,915 10,940 11,160 11,509 12,212
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   10,152 10,194 10,700 11,145 11,465 10,919 10,924 11,161 11,592 12,246
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 Pennsylvania Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Pennsylvania Index                    
Accumulated Value 10,000   10,164 10,320 10,991 11,428 11,992 11,269 11,247 11,574 11,896 12,698
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   $ 10,182 $ 10,253 $ 10,828 $ 11,346 $ 11,709 $ 11,047 $ 11,042 $ 11,319 $ 11,610 $ 12,368
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