v3.26.3
S000027380 [Member] Expense Example - AB High Income Municipal Portfolio
May 31, 2026
USD ($)
Class A  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year $ 421
Expense Example, with Redemption, 3 Years 680
Expense Example, with Redemption, 5 Years 959
Expense Example, with Redemption, 10 Years 1,753
Class C  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 300 [1]
Expense Example, with Redemption, 3 Years 622
Expense Example, with Redemption, 5 Years 1,071
Expense Example, with Redemption, 10 Years 2,122
Advisor Class  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 99
Expense Example, with Redemption, 3 Years 313
Expense Example, with Redemption, 5 Years 545
Expense Example, with Redemption, 10 Years 1,211
Class Z  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 99
Expense Example, with Redemption, 3 Years 309
Expense Example, with Redemption, 5 Years 536
Expense Example, with Redemption, 10 Years $ 1,190
[1]
If you did not redeem your shares at the end of the period, your expenses would be decreased by approximately $100.