Net Assets Investment Company, Portfolio Turnover Washington Mutual Investors Fund - Class R-2 Standard & Poor's 500 Index [Member] Investment Type [Axis] Financial Services Sector [Member] Healthcare Sector [Member] Other securities [Member] Short Term Securities And Other Assets Less Liabilities [Member] Washington Mutual Investors Fund - Class R-2E Washington Mutual Investors Fund - Class R-3 Washington Mutual Investors Fund Class R-4 Washington Mutual Investors Fund Class R-5E Washington Mutual Investors Fund - Class R-5 Washington Mutual Investors Fund - Class R-6 C000025719 [Member] Washington Mutual Investors Fund - Class A Washington Mutual Investors Fund - Class C Washington Mutual Investors Fund - Class T Washington Mutual Investors Fund - Class F-1 Washington Mutual Investors Fund - Class F-2 Washington Mutual Investors Fund - Class F-3 Washington Mutual Investors Fund - Class 529-A Washington Mutual Investors Fund - Class 529-C Washington Mutual Investors Fund - Class 529-E Washington Mutual Investors Fund - Class 529-T Washington Mutual Investors Fund - Class 529-F-1 Washington Mutual Investors Fund - Class 529-F-2 Washington Mutual Investors Fund - Class 529-F-3 WASHINGTON MUTUAL INVESTORS FUND Class R-1