Net Assets Investment Company, Portfolio Turnover C000077851 [Member] American Mutual Fund® - Class R-6 C000024452 [Member] American Mutual Fund® - Class R-3 C000024453 [Member] American Mutual Fund® - Class R-4 C000164809 [Member] American Mutual Fund® - Class R-5E C000024454 [Member] American Mutual Fund® - Class R-5 C000024449 [Member] American Mutual Fund® - Class A C000024456 [Member] American Mutual Fund® - Class C C000186125 [Member] American Mutual Fund® - Class T C000024457 [Member] American Mutual Fund® - Class F-1 C000068556 [Member] American Mutual Fund® - Class F-2 C000176470 [Member] American Mutual Fund® - Class F-3 C000024458 [Member] American Mutual Fund® - Class 529-A C000024460 [Member] American Mutual Fund® - Class 529-C C000024461 [Member] American Mutual Fund® - Class 529-E C000186124 [Member] American Mutual Fund® - Class 529-T C000024462 [Member] American Mutual Fund® - Class 529-F-1 C000190067 [Member] American Mutual Fund® - Class 529-F-2 C000190068 [Member] American Mutual Fund® - Class 529-F-3 C000024450 [Member] American Mutual Fund® - Class R-1 C000024451 [Member] American Mutual Fund® - Class R-2 C000148452 [Member] American Mutual Fund® - Class R-2E Investment Type [Axis] Healthcare Sector [Member] Financial Services Sector [Member] Other securities [Member] Short-term securities and other assets less liabilities [Member]