S000010778 [Member] Average Annual Total Returns	3 Months Ended	12 Months Ended	60 Months Ended	94 Months Ended	120 Months Ended	146 Months Ended	374 Months Ended	375 Months Ended
S000010778 [Member] Average Annual Total Returns	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2024
Bloomberg 1-5 Year Municipal Bond Index (reflects no deductions for fees, expenses or taxes)
Prospectus [Line Items]
Average Annual Return, Percent		2.07%	1.10%		1.38%
Bloomberg Municipal Bond Index (reflects no deductions for fees, expenses or taxes)
Prospectus [Line Items]
Average Annual Return, Percent		1.05%	0.99%		2.25%
C000029792 [Member]
Prospectus [Line Items]
Average Annual Return, Percent		1.23%	0.67%		0.88%
Performance Inception Date							Nov. 02, 1993
C000029792 [Member] \| After Taxes on Distributions
Prospectus [Line Items]
Average Annual Return, Percent		1.23%	0.67%		0.88%
Performance Inception Date							Nov. 02, 1993
C000029792 [Member] \| After Taxes on Distributions and Sales
Prospectus [Line Items]
Average Annual Return, Percent		1.75%	0.86%		0.97%
Performance Inception Date							Nov. 02, 1993
C000029795 [Member]
Prospectus [Line Items]
Average Annual Return, Percent		2.49%	1.13%		1.23%
Performance Inception Date								Oct. 07, 1993
C000122570 [Member]
Prospectus [Line Items]
Average Annual Return, Percent		2.44%	1.16%		1.29%
Performance Inception Date						Nov. 08, 2012
C000174632 [Member]
Prospectus [Line Items]
Average Annual Return, Percent		2.48%	1.21%		1.30%
Performance Inception Date				Mar. 01, 2017
C000255076 [Member]
Prospectus [Line Items]
Average Annual Return, Percent		2.48%	1.13%		1.23%
Performance Inception Date	Oct. 02, 2024