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
C000199773 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class K Shares                    
Accumulated Value $ 10,000   $ 10,188 $ 10,635 $ 11,104 $ 10,896 $ 11,911 $ 11,194 $ 11,225 $ 11,723 $ 11,950 $ 12,651
C000038562 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Investor C Shares (with sales charge)                    
Accumulated Value 10,000   10,087 10,423 10,761 10,457 11,311 10,520 10,439 10,789 10,955 11,574
C000011299 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Investor A1 Shares                    
Accumulated Value 10,000   10,178 10,620 11,064 10,842 11,845 11,117 11,133 11,611 11,819 12,495
C000038561 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Investor A Shares (with sales charge)                    
Accumulated Value 9,575   9,731 10,139 10,546 10,317 11,255 10,546 10,544 10,980 11,150 11,780
C000011302 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Institutional Shares                    
Accumulated Value 10,000   10,188 10,633 11,088 10,883 11,891 11,170 11,196 11,686 11,896 12,598
Bloomberg Municipal Bond Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Bloomberg Municipal Bond Index                    
Accumulated Value $ 10,000   $ 10,146 $ 10,259 $ 10,916 $ 11,350 $ 11,888 $ 11,080 $ 11,134 $ 11,432 $ 11,664 $ 12,442
California Customized Reference Benchmark [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   California Customized Reference Benchmark