Shareholder Report, Average Annual Return (Details) |
12 Months Ended | 60 Months Ended | 120 Months Ended |
|---|---|---|---|
Aug. 31, 2026 |
Aug. 31, 2026 |
Aug. 31, 2026 |
|
| C000007079 | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Investor Shares | ||
| Without Sales Load [Member] | C000007079 | |||
| Average Annual Return [Line Items] | |||
| Average Annual Return, Percent | 2.48% | 2.38% | 1.64% |
| NACC2 Index: Bloomberg Municipal Bond Index | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||
| Average Annual Return, Percent | 4.12% | 0.54% | 1.91% |
| NACC2 Index: Short Municipal Debt Funds Average | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Short Municipal Debt Funds Average | ||
| Average Annual Return, Percent | 2.34% | 1.80% | 1.55% |