Shareholder Report, Average Annual Return (Details)	12 Months Ended	60 Months Ended	120 Months Ended
Shareholder Report, Average Annual Return (Details)	Jun. 30, 2025	Jun. 30, 2025	Jun. 30, 2025
C000011316 [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Institutional Shares
Average Annual Return, Percent	(0.86%)	1.79%	2.47%
C000038358 [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Investor A Shares (with sales charge)
Average Annual Return, Percent	(5.40%)	0.64%	1.76%
C000011313 [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Investor A1 Shares
Average Annual Return, Percent	(1.05%)	1.67%	2.35%
C000038359 [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Investor C Shares (with sales charge)
Average Annual Return, Percent	(2.80%)	0.77%	1.59%
C000199771 [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Class K Shares
Average Annual Return, Percent	(0.81%)	1.84%	2.50%
Without Sales Load [Member] \| C000038358 [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Investor A Shares
Average Annual Return, Percent	(1.20%)	1.52%	2.20%
Without Sales Load [Member] \| C000038359 [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Investor C Shares
Average Annual Return, Percent	(1.84%)	0.77%	1.59%
Bloomberg Municipal Bond Index [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Bloomberg Municipal Bond Index
Average Annual Return, Percent	1.11%	0.51%	2.20%
Customized Reference Benchmark [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Customized Reference Benchmark
Average Annual Return, Percent	0.87%	0.76%