Shareholder Report, Holdings (Details)	Aug. 31, 2025
C000005541 \| Virginia
Holdings [Line Items]
Percent of Net Asset Value	81.80%
C000005541 \| District of Columbia
Holdings [Line Items]
Percent of Net Asset Value	12.60%
C000005541 \| Puerto Rico
Holdings [Line Items]
Percent of Net Asset Value	5.40%
C000005541 \| Other Holdings Grouping
Holdings [Line Items]
Percent of Net Asset Value	0.20%
C000005541 \| Hospital Revenue
Holdings [Line Items]
Percent of Net Asset Value	22.40%
C000005541 \| Air & Sea Transportation
Holdings [Line Items]
Percent of Net Asset Value	20.70%
C000005541 \| Dedicated Tax Revenue
Holdings [Line Items]
Percent of Net Asset Value	10.10%
C000005541 \| Housing Finance Revenue
Holdings [Line Items]
Percent of Net Asset Value	8.90%
C000005541 \| Educational Revenue
Holdings [Line Items]
Percent of Net Asset Value	8.70%
C000005541 \| Lease Revenue
Holdings [Line Items]
Percent of Net Asset Value	7.90%
C000005541 \| General Obligations - Local
Holdings [Line Items]
Percent of Net Asset Value	7.00%
C000005541 \| Water & Sewer Revenue
Holdings [Line Items]
Percent of Net Asset Value	6.50%
C000005541 \| General Obligations - State
Holdings [Line Items]
Percent of Net Asset Value	2.70%
C000005541 \| Other 2
Holdings [Line Items]
Percent of Net Asset Value	5.10%
C000193180 \| Virginia
Holdings [Line Items]
Percent of Net Asset Value	81.80%
C000193180 \| District of Columbia
Holdings [Line Items]
Percent of Net Asset Value	12.60%
C000193180 \| Puerto Rico
Holdings [Line Items]
Percent of Net Asset Value	5.40%
C000193180 \| Other Holdings Grouping
Holdings [Line Items]
Percent of Net Asset Value	0.20%
C000193180 \| Hospital Revenue
Holdings [Line Items]
Percent of Net Asset Value	22.40%
C000193180 \| Air & Sea Transportation
Holdings [Line Items]
Percent of Net Asset Value	20.70%
C000193180 \| Dedicated Tax Revenue
Holdings [Line Items]
Percent of Net Asset Value	10.10%
C000193180 \| Housing Finance Revenue
Holdings [Line Items]
Percent of Net Asset Value	8.90%
C000193180 \| Educational Revenue
Holdings [Line Items]
Percent of Net Asset Value	8.70%
C000193180 \| Lease Revenue
Holdings [Line Items]
Percent of Net Asset Value	7.90%
C000193180 \| General Obligations - Local
Holdings [Line Items]
Percent of Net Asset Value	7.00%
C000193180 \| Water & Sewer Revenue
Holdings [Line Items]
Percent of Net Asset Value	6.50%
C000193180 \| General Obligations - State
Holdings [Line Items]
Percent of Net Asset Value	2.70%
C000193180 \| Other 2
Holdings [Line Items]
Percent of Net Asset Value	5.10%