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 |
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| C000024678 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Service Shares | |||||||||||
| Accumulated Value | $ 10,000 | $ 10,025 | $ 10,120 | $ 10,369 | $ 10,465 | $ 10,674 | $ 10,188 | $ 10,358 | $ 10,721 | $ 11,095 | $ 11,496 | |
| C000024677 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Institutional Shares | |||||||||||
| Accumulated Value | 10,000 | 10,049 | 10,159 | 10,445 | 10,557 | 10,804 | 10,336 | 10,534 | 10,929 | 11,337 | 11,764 | |
| C000037571 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class A Shares with sales load | |||||||||||
| Accumulated Value | 9,900 | 9,913 | 9,972 | 10,191 | 10,274 | 10,478 | 9,989 | 10,165 | 10,510 | 10,875 | 11,268 | |
| Morningstar US Fund Muni National Short Funds Category Average [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Morningstar US Fund Muni National Short Funds Category Average | |||||||||||
| Accumulated Value | 10,000 | 10,014.34 | 10,078.90946 | 10,365.18677 | 10,572.66361 | 10,752.74461 | 10,421.3504 | 10,597.38889 | 10,941.17985 | 11,314.50056 | 11,703.66168 | |
| 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 | 10,043.27987 | 10,094.67358 | 10,458.27743 | 10,777.22461 | 10,930.85515 | 10,565.9206 | 10,682.32454 | 10,975.34051 | 11,426.60836 | 11,798.93027 | |
| 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 | 10,054.158 | 10,123.44623 | 10,427.35512 | 10,704.43289 | 10,821.04377 | 10,585.24781 | 10,712.23268 | 11,031.37366 | 11,471.86413 | 11,806.20473 | |
| 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 | $ 9,971.691 | $ 10,132.72284 | $ 10,779.73874 | $ 11,235.59772 | $ 11,707.09396 | $ 10,781.3157 | $ 11,094.68327 | $ 11,493.7801 | $ 11,672.36126 | $ 12,443.38026 | |