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
C000001556 [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 $ 10,158 $ 10,214 $ 10,786 $ 11,183 $ 11,670 $ 10,671 $ 10,558 $ 10,803 $ 10,867
C000001559 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,582 10,640 10,732 11,352 11,793 12,331 11,304 11,201 11,476 11,571
C000001551 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,548 10,505 10,598 11,200 11,603 12,210 11,174 11,030 11,353 11,457
C000001548 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,583   10,090 10,033 10,095 10,649 11,013 11,565 10,563 10,396 10,691 10,758
C000001552 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares at maximum sales charge (Offering Price)                    
Accumulated Value 9,580   10,139 10,105 10,323 10,922 11,111 11,898 11,230 11,171 11,664 11,590
C000001555 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares at NAV                    
Accumulated Value 10,000   10,595 10,591 10,842 11,484 11,708 12,561 11,893 11,847 12,397 12,345
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 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 North Carolina Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond North Carolina Index                    
Accumulated Value 10,000   10,473 10,618 10,666 11,238 11,756 12,125 11,392 11,404 11,636 11,984
S And P Municipal Bond Louisiana Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Louisiana Index                    
Accumulated Value 10,000   10,499 10,650 10,783 11,401 11,793 12,437 11,844 11,899 12,301 12,609
S And P Municipal Bond Georgia Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   S&P Municipal Bond Georgia Index                    
Accumulated Value $ 10,000   $ 10,520 $ 10,655 $ 10,737 $ 11,332 $ 11,757 $ 12,236 $ 11,474 $ 11,507 $ 11,850 $ 12,225