AMERICAN HIGH-INCOME MUNICIPAL BOND FUND (Class A, Class C, Class F-1, Class F-2, Class F-3) AMERICAN HIGH-INCOME MUNICIPAL BOND FUND (Class R6) AMERICAN HIGH-INCOME MUNICIPAL BOND FUND Class A Class C Class F-1 Class F-2 Class F-3 Class R-6 Market conditions [Member] Issuer risks [Member] Investing in municipal securities [Member] Investing in debt instruments [Member] Liquidity risk [Member] Credit and liquidity support [Member] Investing in lower rated debt instruments [Member] Investing in similar municipal bonds [Member] Management [Member] Bloomberg Municipal Bond Index (reflects no deductions for sales charges, account fees, expenses or U.S. federal income taxes) Investing In Lower Rated Debt Instruments Member Issuer Risks Member C000025078 Member C000114834 Member Credit And Liquidity Support Member index_ Bloomberg_ Municipal_ Bond_ Index_reflects_no_deductions_for_sales_charges_account_fees_expenses_or_ US_federal_income_taxes Member Market Conditions Member C000025081 Member Investing In Similar Municipal Bonds Member C000179998 Member ManagementMember C000025080 Member S000009229 Member C000068565 Member Investing In Debt Instruments Member doc_ AMERICAN_ HIGHINCOME_ MUNICIPAL_ BOND_ FUND_ Class_ R6 Member doc_ AMERICAN_ HIGHINCOME_ MUNICIPAL_ BOND_ FUND_ Class_ A_ Class_ C_ Class_ F1_ Class_ F2_ Class_ F3 Member Investing In Municipal Securities Member Liquidity Risk Member