Shareholder Report, Holdings (Details)	Feb. 28, 2026
C000005541 \| Virginia
Holdings [Line Items]
Percent of Net Asset Value	82.00%
C000005541 \| District of Columbia
Holdings [Line Items]
Percent of Net Asset Value	12.40%
C000005541 \| Puerto Rico
Holdings [Line Items]
Percent of Net Asset Value	5.80%
C000005541 \| Arizona
Holdings [Line Items]
Percent of Net Asset Value	0.50%
C000005541 \| Missouri
Holdings [Line Items]
Percent of Net Asset Value	0.10%
C000005541 \| Other Holdings Grouping
Holdings [Line Items]
Percent of Net Asset Value	(0.80%)
C000005541 \| Hospital Revenue
Holdings [Line Items]
Percent of Net Asset Value	21.00%
C000005541 \| Ground Transportation Revenue
Holdings [Line Items]
Percent of Net Asset Value	20.40%
C000005541 \| Educational Revenue
Holdings [Line Items]
Percent of Net Asset Value	10.40%
C000005541 \| Dedicated Tax Revenue
Holdings [Line Items]
Percent of Net Asset Value	9.80%
C000005541 \| Lease Revenue
Holdings [Line Items]
Percent of Net Asset Value	9.30%
C000005541 \| Housing Finance Revenue
Holdings [Line Items]
Percent of Net Asset Value	8.90%
C000005541 \| General Obligations - Local
Holdings [Line Items]
Percent of Net Asset Value	8.60%
C000005541 \| Water & Sewer Revenue
Holdings [Line Items]
Percent of Net Asset Value	5.70%
C000005541 \| General Obligations - State
Holdings [Line Items]
Percent of Net Asset Value	2.40%
C000005541 \| Other 2
Holdings [Line Items]
Percent of Net Asset Value	3.50%
C000193180 \| Virginia
Holdings [Line Items]
Percent of Net Asset Value	82.00%
C000193180 \| District of Columbia
Holdings [Line Items]
Percent of Net Asset Value	12.40%
C000193180 \| Puerto Rico
Holdings [Line Items]
Percent of Net Asset Value	5.80%
C000193180 \| Arizona
Holdings [Line Items]
Percent of Net Asset Value	0.50%
C000193180 \| Missouri
Holdings [Line Items]
Percent of Net Asset Value	0.10%
C000193180 \| Other Holdings Grouping
Holdings [Line Items]
Percent of Net Asset Value	(0.80%)
C000193180 \| Hospital Revenue
Holdings [Line Items]
Percent of Net Asset Value	21.00%
C000193180 \| Ground Transportation Revenue
Holdings [Line Items]
Percent of Net Asset Value	20.40%
C000193180 \| Educational Revenue
Holdings [Line Items]
Percent of Net Asset Value	10.40%
C000193180 \| Dedicated Tax Revenue
Holdings [Line Items]
Percent of Net Asset Value	9.80%
C000193180 \| Lease Revenue
Holdings [Line Items]
Percent of Net Asset Value	9.30%
C000193180 \| Housing Finance Revenue
Holdings [Line Items]
Percent of Net Asset Value	8.90%
C000193180 \| General Obligations - Local
Holdings [Line Items]
Percent of Net Asset Value	8.60%
C000193180 \| Water & Sewer Revenue
Holdings [Line Items]
Percent of Net Asset Value	5.70%
C000193180 \| General Obligations - State
Holdings [Line Items]
Percent of Net Asset Value	2.40%
C000193180 \| Other 2
Holdings [Line Items]
Percent of Net Asset Value	3.50%