S000000288 [Member] Average Annual Total Returns

12 Months Ended

60 Months Ended

120 Months Ended

131 Months Ended

335 Months Ended

446 Months Ended

Dec. 31, 2024

Dec. 31, 2024

Dec. 31, 2024

Dec. 31, 2024

Dec. 31, 2024

Dec. 31, 2024

S&P Municipal Bond Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

Average Annual Return, Percent

^[1]

1.90%

1.20%

2.34%

S&P Municipal Bond Short-Intermediate Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

Average Annual Return, Percent

^[2]

1.89%

1.13%

1.65%

Lipper Short-Intermediate Municipal Debt Funds Classification Average (reflects no deduction for taxes or sales loads)

Prospectus [Line Items]

Average Annual Return, Percent

^[3]

2.12%

1.00%

1.31%

Class A

Prospectus [Line Items]

Average Annual Return, Percent

(1.09%)

0.53%

1.29%

Performance Inception Date

Oct. 19, 1987

Class A | After Taxes on Distributions

Prospectus [Line Items]

Average Annual Return, Percent

(1.12%)

0.52%

1.28%

Performance Inception Date

Oct. 19, 1987

Class A | After Taxes on Distributions and Sales

Prospectus [Line Items]

Average Annual Return, Percent

0.30%

0.79%

1.39%

Performance Inception Date

Oct. 19, 1987

Class I

Prospectus [Line Items]

Average Annual Return, Percent

1.55%

1.24%

1.75%

Performance Inception Date

Feb. 06, 1997

Class C

Prospectus [Line Items]

Average Annual Return, Percent

0.56%

0.25%

0.92%

Performance Inception Date

Feb. 10, 2014

[1]	An index designed to measure the performance of the tax-exempt U.S. municipal bond market.
[2]	An index containing bonds in the S&P Municipal Bond Index that mature between 1 and 8 years.
[3]	Represents the average annualized total return for all reporting funds in the Lipper Short-Intermediate Municipal Debt Funds Classification.