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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Jun. 30, 2016 |
Jun. 30, 2026 |
Jun. 30, 2017 |
Jun. 30, 2018 |
Jun. 30, 2019 |
Jun. 30, 2020 |
Jun. 30, 2021 |
Jun. 30, 2022 |
Jun. 30, 2023 |
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2026 |
|
| C000199771 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class K Shares | |||||||||||
| Accumulated Value | $ 10,000 | $ 9,991 | $ 10,385 | $ 10,906 | $ 10,648 | $ 11,678 | $ 10,717 | $ 11,073 | $ 11,759 | $ 11,663 | $ 12,605 | |
| C000038359 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Investor C Shares (with sales charge) | |||||||||||
| Accumulated Value | 10,000 | 9,891 | 10,178 | 10,576 | 10,219 | 11,099 | 10,071 | 10,297 | 10,820 | 10,691 | 11,531 | |
| C000011313 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Investor A1 Shares | |||||||||||
| Accumulated Value | 10,000 | 9,981 | 10,362 | 10,865 | 10,603 | 11,610 | 10,630 | 10,978 | 11,639 | 11,517 | 12,440 | |
| C000038358 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Investor A Shares (with sales charge) | |||||||||||
| Accumulated Value | 9,575 | 9,534 | 9,893 | 10,357 | 10,083 | 11,024 | 10,079 | 10,393 | 11,003 | 10,871 | 11,725 | |
| C000011316 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Institutional Shares | |||||||||||
| Accumulated Value | 10,000 | 9,991 | 10,383 | 10,898 | 10,636 | 11,668 | 10,694 | 11,044 | 11,722 | 11,621 | 12,565 | |
| Bloomberg Municipal Bond Index [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Accumulated Value | $ 10,000 | $ 9,951 | $ 10,107 | $ 10,785 | $ 11,264 | $ 11,734 | $ 10,728 | $ 11,070 | $ 11,425 | $ 11,553 | $ 12,365 | |
| Customized Reference Benchmark [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Customized Reference Benchmark | |||||||||||