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, 2015 |
Jun. 30, 2025 |
Jun. 30, 2016 |
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 |
|
| C000037571 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class A Shares with sales load | |||||||||||
| Accumulated Value | $ 9,900 | $ 10,015 | $ 10,024 | $ 10,084 | $ 10,305 | $ 10,389 | $ 10,595 | $ 10,100 | $ 10,279 | $ 10,627 | $ 10,997 | |
| C000024677 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Institutional Shares | |||||||||||
| Accumulated Value | 10,000 | 10,163 | 10,213 | 10,325 | 10,615 | 10,729 | 10,980 | 10,504 | 10,705 | 11,107 | 11,522 | |
| C000024678 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Service Shares | |||||||||||
| Accumulated Value | 10,000 | 10,139 | 10,163 | 10,260 | 10,513 | 10,611 | 10,822 | 10,329 | 10,501 | 10,870 | 11,249 | |
| 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 | 10,780.331 | 10,749.81296 | 10,923.41062 | 11,620.91517 | 12,112.34624 | 12,620.63479 | 11,622.61519 | 11,960.4358 | 12,390.6754 | 12,583.1918 | |
| S And P Municipal Bond Short Index [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | S&P Municipal Bond Short Index | |||||||||||
| Accumulated Value | 10,000 | 10,174.734 | 10,229.83832 | 10,300.33726 | 10,609.55647 | 10,891.47573 | 11,010.1242 | 10,770.20808 | 10,899.41181 | 11,224.12926 | 11,672.3166 | |
| S And P Municipal Bond 1 5 Years Investment Grade 5 Pre Refunded Index [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | S&P Municipal Bond 1-5 Years Investment Grade 5% Pre-Refunded Index | |||||||||||
| Accumulated Value | 10,000 | 10,245.18307 | 10,289.52409 | 10,342.17789 | 10,714.69669 | 11,041.46391 | 11,198.86122 | 10,824.97909 | 10,944.23705 | 11,244.43728 | 11,706.76945 | |
| Morningstar US Fund Muni National Short Funds Average [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Morningstar US Fund Muni National Short Funds Average | |||||||||||
| Accumulated Value | $ 10,000 | $ 10,193.901 | $ 10,208.51905 | $ 10,274.34052 | $ 10,566.16878 | $ 10,777.66861 | $ 10,961.24141 | $ 10,623.42143 | $ 10,802.87333 | $ 11,153.33042 | $ 11,533.88986 | |