Net Assets Investment Company, Portfolio Turnover C000023985 [Member] The Income Fund of America - Class A [Member] C000023992 [Member] The Income Fund of America - Class C [Member] C000023993 [Member] The Income Fund of America - Class F-1 [Member] C000068581 [Member] The Income Fund of America - Class F-2 [Member] C000179951 [Member] The Income Fund of America - Class F-3 [Member] C000023994 [Member] The Income Fund of America - Class 529-A [Member] C000023996 [Member] The Income Fund of America - Class 529-C [Member] C000023997 [Member] The Income Fund of America - Class 529-E [Member] C000223653 [Member] The Income Fund of America - Class 529-F-2 [Member] C000223654 [Member] The Income Fund of America - Class 529-F-3 [Member] C000023986 [Member] The Income Fund of America - Class R-1 [Member] C000023987 [Member] The Income Fund of America - Class R-2 [Member] C000148385 [Member] The Income Fund of America - Class R-2E [Member] C000023988 [Member] The Income Fund of America - Class R-3 [Member] C000023989 [Member] The Income Fund of America - Class R-4 [Member] C000164804 [Member] The Income Fund of America - Class R-5E [Member] C000023990 [Member] The Income Fund of America - Class R-5 [Member] C000077898 [Member] The Income Fund of America - Class R-6 [Member] 65%/35% S&P 500 Index/Bloomberg U.S. Aggregate Index [Member] Bloomberg U.S. Aggregate Index [Member] StandardPoors500IndexMember Investment Type [Axis] Common Stock [Member] U.S. corporate bonds & notes [Member] Corporate Bonds Notes And Loans Of Issuers Outside The US [Member] Corporate bonds notes & loans of issuers outside the U.S. [Member] U.S. Treasury bonds & notes [Member] Mortgage-backed obligations [Member] Asset-backed obligations [Member] Loans [Member] Bonds And Notes Of Governments And Government Agencies Outside The US [Member] Bonds & notes of governments & government agencies outside the U.S. [Member] Municipals [Member] Other Securities [Member] Short Term Securities And Other Assets Less Liabilities [Member] Short-term securities & other assets less liabilities [Member]