v3.26.3
Shareholder Report, Average Annual Return (Details)
 12 Months Ended 60 Months Ended 114 Months Ended 120 Months Ended
Jul. 31, 2026
Jul. 31, 2026
Jul. 31, 2026
 [2]
Jul. 31, 2026
American High-Income Municipal Bond Fund® - Class A        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name American High-Income Municipal Bond Fund — Class A (with sales charge)      
Average Annual Return, Percent [1] 3.04% 0.58%   2.68%
American High-Income Municipal Bond Fund® - Class C        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name American High-Income Municipal Bond Fund — Class C (with sales charge)      
Average Annual Return, Percent [1] 5.30% 0.63%   2.47%
American High-Income Municipal Bond Fund® - Class F-1        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name American High-Income Municipal Bond Fund — Class F-1      
Average Annual Return, Percent [1] 7.04% 1.33%   3.03%
American High-Income Municipal Bond Fund® - Class F-2        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name American High-Income Municipal Bond Fund — Class F-2      
Average Annual Return, Percent [1] 7.31% 1.59%   3.30%
American High-Income Municipal Bond Fund® - Class F-3        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name American High-Income Municipal Bond Fund — Class F-3      
Average Annual Return, Percent [1] 7.43% 1.70% 4.00%  
American High-Income Municipal Bond Fund® - Class R-6        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name American High-Income Municipal Bond Fund — Class R-6      
Average Annual Return, Percent [1] 7.42% 1.70%   3.41%
Without Sales Load [Member] | American High-Income Municipal Bond Fund® - Class A        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name American High-Income Municipal Bond Fund — Class A (without sales charge)      
Average Annual Return, Percent [1] 7.06% 1.35%   3.07%
Without Sales Load [Member] | American High-Income Municipal Bond Fund® - Class C        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name American High-Income Municipal Bond Fund — Class C (without sales charge)      
Average Annual Return, Percent [1] 6.30% 0.63%   2.47%
Bloomberg Municipal Bond Index [Member]        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name Bloomberg Municipal Bond Index      
Average Annual Return, Percent [3] 5.27% 0.51% 2.43% 1.95%
[1] Investment results assume all distributions are reinvested and reflect applicable fees and expenses. When applicable, results reflect fee waivers and/or expense reimbursements, without which they would have been lower.
[2] Class F-3 shares were first offered on January 27, 2017.
[3] Results assume all distributions are reinvested. Any market index shown is unmanaged, and therefore, has no expenses. Investors cannot invest directly in an index. Source(s): Bloomberg Index Services Ltd.