| Shareholder Report | 12 Months Ended |
| Oct. 31, 2024 USD ($) Holding |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | American Mutual Fund |
| Entity Central Index Key | 0000005506 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Oct. 31, 2024 |
| American Mutual Fund - Class A | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class A |
| Trading Symbol | AMRMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-A |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-A |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $ 0.58 % |
| Expenses Paid, Amount | $ 66 |
| Expense Ratio, Percent | 0.58% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class A shares gained 29.06% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including capitalgroup.com/mutual-fund-returns-A What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class A (with sales charge) * 21.65 % 9.51 % 9.05 % American Mutual Fund — Class A (without sales charge) * 29.06 % 10.81 % 9.70 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * applicable † distributions shown index |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class C | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class C |
| Trading Symbol | AMFCX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-C |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-C |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $ 1.33 % |
| Expenses Paid, Amount | $ 152 |
| Expense Ratio, Percent | 1.33% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class C shares gained 28.11% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-C What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health c ar Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fu nd’ |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class C (with sales charge) * 27.11 % 9.99 % 9.02 % American Mutual Fund — Class C (without sales charge) * 28.11 % 9.99 % 9.02 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * d an † ndex |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund sta tist Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector cen |
| American Mutual Fund - Class T | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class T |
| Trading Symbol | TAMFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class T $ 0.33 % |
| Expenses Paid, Amount | $ 38 |
| Expense Ratio, Percent | 0.33% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class T shares gained 29.39% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials , i Conversely, while consumer staples, energy and communicati on s |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average an nu 1 year 5 years Since inception 1 American Mutual Fund — Class T (with sales charge) 2 26.15 % 10.54 % 10.43% American Mutual Fund — Class T (without sales charge) 2 29.39 % 11.10 % 10.80% S&P 500 Index 3 38.02 % 15.27 % 14.36 % 1 2 lower 3 |
| Performance Inception Date | Apr. 07, 2017 |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key f u Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector e |
| American Mutual Fund - Class F-1 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class F-1 |
| Trading Symbol | AMFFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-F1 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-F1 |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class F-1 $ 0.64 % |
| Expenses Paid, Amount | $ 73 |
| Expense Ratio, Percent | 0.64% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class F-1 shares gained 28.99% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-F1 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, le d Conversely, while consumer staples, energy a n |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual tot 1 year 5 years 10 years American Mutual Fund — Class F-1 * 28.99 % 10.76 % 9.63 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fu n Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sec to |
| American Mutual Fund - Class F-2 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class F-2 |
| Trading Symbol | AMRFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-F2 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-F2 |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class F-2 $ 0.38 % |
| Expenses Paid, Amount | $ 44 |
| Expense Ratio, Percent | 0.38% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class F-2 shares gained 29.32% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-F2 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class F-2 * 29.32 % 11.04 % 9.91 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class F-3 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class F-3 |
| Trading Symbol | AFMFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-F3 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-F3 |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class F-3 $ 0.27 % |
| Expenses Paid, Amount | $ 31 |
| Expense Ratio, Percent | 0.27% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class F-3 shares gained 29.46% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-F3 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years Since inception 1 American Mutual Fund — Class F-3 2 29.46 % 11.16 % 10.94 % S&P 500 Index 3 38.02 % 15.27 % 14.43 % 1 2 3 est |
| Performance Inception Date | Jan. 27, 2017 |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class 529-A | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class 529-A |
| Trading Symbol | CMLAX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-529A |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-529A |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class 529-A $ 0.61 % |
| Expenses Paid, Amount | $ 70 |
| Expense Ratio, Percent | 0.61% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-A shares gained 29.03% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529A What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some inco m |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class 529-A (with sales charge) * 24.52 % 9.99 % 9.25 % American Mutual Fund — Class 529-A (without sales charge) * 29.03 % 10.78 % 9.64 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † expenses cannot |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class 529-C | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class 529-C |
| Trading Symbol | CMLCX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-529C |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-529C |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class 529-C $ 1.37 % |
| Expenses Paid, Amount | $ 156 |
| Expense Ratio, Percent | 1.37% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-C shares gained 28.05% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529C What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class 529-C * 27.05 % 9.95 % 9.22 % American Mutual Fund — Class 529-C (without sales charge) * 28.05 % 9.95 % 9.22 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector assets |
| American Mutual Fund - Class 529-E | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class 529-E |
| Trading Symbol | CMLEX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-529E |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-529E |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class 529-E $ 0.85 % |
| Expenses Paid, Amount | $ 97 |
| Expense Ratio, Percent | 0.85% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-E shares gained 28.71% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529E What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class 529-E * 28.71 % 10.51 % 9.38 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector percent assets |
| American Mutual Fund - Class 529-T | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class 529-T |
| Trading Symbol | TAFMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class 529-T $ 0.38 % |
| Expenses Paid, Amount | $ 44 |
| Expense Ratio, Percent | 0.38% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-T shares gained 29.33% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years Since inception 1 American Mutual Fund — Class 529-T (with sales charge) 2 26.10 % 10.48 % 10.37 % American Mutual Fund — Class 529-T (without sales charge) 2 29.33 % 11.04 % 10.74 % S&P 500 Index 3 38.02 % 15.27 % 14.36 % 1 2 3 |
| Performance Inception Date | Apr. 07, 2017 |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class 529-F-1 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class 529-F-1 |
| Trading Symbol | CMLFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-529F1 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-529F1 |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class 529-F-1 $ 0.44 % |
| Expenses Paid, Amount | $ 50 |
| Expense Ratio, Percent | 0.44% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-F-1 shares gained 29.24% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529F1 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class 529-F-1 * 29.24 % 10.99 % 9.86 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector assets |
| American Mutual Fund - Class 529-F-2 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class 529-F-2 |
| Trading Symbol | FFMMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-529F2 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-529F2 |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class 529-F-2 $ 0.36 % |
| Expenses Paid, Amount | $ 41 |
| Expense Ratio, Percent | 0.36% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-F-2 shares gained 29.34% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529F2 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year Since inception 1 American Mutual Fund — Class 529-F-2 2 29.34 % 14.32 % S&P 500 Index 3 38.02 % 16.69 % 1 2 and 3 directly |
| Performance Inception Date | Oct. 30, 2020 |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector assets |
| American Mutual Fund - Class 529-F-3 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class 529-F-3 |
| Trading Symbol | FFFMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-529F3 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-529F3 |
| Expenses [Text Block] | What were the fund costs for the last year ? hypothetical Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class 529-F-3 $ 0.32 % |
| Expenses Paid, Amount | $ 37 |
| Expense Ratio, Percent | 0.32% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-F-3 shares gained 29.40% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529F3 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year Since inception 1 American Mutual Fund — Class 529-F-3 2 29.40 % 14.37 % S&P 500 Index 3 38.02 % 16.69 % 1 2 3 Investors |
| Performance Inception Date | Oct. 30, 2020 |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class R-1 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class R-1 |
| Trading Symbol | RMFAX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-R1 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-R1 |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-1 $ 1.35 % |
| Expenses Paid, Amount | $ 154 |
| Expense Ratio, Percent | 1.35% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-1 shares gained 28.08% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R1 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class R-1 * 28.08 % 9.95 % 8.82 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * reflect † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class R-2 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class R-2 |
| Trading Symbol | RMFBX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-R2 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-R2 |
| Expenses [Text Block] | What were the fund costs for the last year ? investment Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-2 $ 1.35 % |
| Expenses Paid, Amount | $ 154 |
| Expense Ratio, Percent | 1.35% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-2 shares gained 28.10% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R2 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class R-2 * 28.10 % 9.97 % 8.84 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector assets |
| American Mutual Fund - Class R-2E | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class R-2E |
| Trading Symbol | RMEBX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-R2E |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-R2E |
| Expenses [Text Block] | What were the fund costs for the last year ? m Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-2E $ 1.07 % |
| Expenses Paid, Amount | $ 122 |
| Expense Ratio, Percent | 1.07% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-2E shares gained 28.44% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R2E What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class R-2E * 28.44 % 10.28 % 9.18 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class R-3 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class R-3 |
| Trading Symbol | RMFCX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-R3 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-R3 |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-3 $ 0.91 % |
| Expenses Paid, Amount | $ 104 |
| Expense Ratio, Percent | 0.91% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-3 shares gained 28.66% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R3 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class R-3 * 28.66 % 10.45 % 9.32 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class R-4 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class R-4 |
| Trading Symbol | RMFEX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-R4 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-R4 |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-4 $ 0.61 % |
| Expenses Paid, Amount | $ 70 |
| Expense Ratio, Percent | 0.61% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-4 shares gained 29.02% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R4 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class R-4 * 29.02 % 10.78 % 9.65 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class R-5E | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class R-5E |
| Trading Symbol | RMFHX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-R5E |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-R5E |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-5E $ 0.42 % |
| Expenses Paid, Amount | $ 48 |
| Expense Ratio, Percent | 0.42% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-5E shares gained 29.28% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R5E What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years Since inception 1 American Mutual Fund — Class R-5E 2 29.28 % 11.02 % 10.88 % S&P 500 Index 3 38.02 % 15.27 % 13.90 % 1 2 3 |
| Performance Inception Date | Nov. 20, 2015 |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class R-5 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class R-5 |
| Trading Symbol | RMFFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-R5 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-R5 |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-5 $ 0.32 % |
| Expenses Paid, Amount | $ 37 |
| Expense Ratio, Percent | 0.32% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-5 shares gained 29.42% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S&P 500 Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R5 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class R-5 * 29.42 % 11.11 % 9.98 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
| American Mutual Fund - Class R-6 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Mutual Fund® |
| Class Name | Class R-6 |
| Trading Symbol | RMFGX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Mutual Fund (the "fund") for the period from November 1, 2023 to October 31, 2024. |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the fund at capitalgroup.com/mutual-fund-literature-R6 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-R6 |
| Expenses [Text Block] | What were the fund costs for the last year ? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-6 $ 0.27 % |
| Expenses Paid, Amount | $ 31 |
| Expense Ratio, Percent | 0.27% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-6 shares gained 29.47% for the year ended October 31, 2024. That result compares with a 38.02% gain for the S& capitalgroup.com/mutual-fund-returns-R6 What factors influenced results During the fund’s fiscal year, the U.S. market showed resilience, with positive economic data providing a counterweight to political uncertainties leading into the U.S. presidential election. Domestic equity markets achieved notable gains during the period. Consumer spending and labor market data did not disappoint as much as some feared it would , while easing inflation supported the U.S. Federal Reserve’s first rate cut since 2020. All sectors created positive results for the fund, led by financials, industrials and utilities. Top individual contributors included holdings from a broad range of sectors, such as industrials, technology, health care and financials. Most holdings are based in the U.S., which contributed positively to results in the fiscal year. Conversely, while consumer staples, energy and communication services sectors posted positive returns, those sectors did not advance as much as others in the fund, and thus detracted from results. The fund’s exposure to cash also detracted from results given the strong returns of the market, despite elevated interest rates producing some income for the fund. |
| Performance Past Does Not Indicate Future [Text] | The fund’s past performance is not a predictor of its future performance. |
| Line Graph [Table Text Block] | |
| Average Annual Return [Table Text Block] | Average annual total returns 1 year 5 years 10 years American Mutual Fund — Class R-6 * 29.47 % 11.17 % 10.03 % S&P 500 Index † 38.02 % 15.27 % 13.00 % * † |
| No Deduction of Taxes [Text Block] | The line chart and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 103,462,000,000 |
| Holdings Count | Holding | 189 |
| Advisory Fees Paid, Amount | $ 221,000,000 |
| Investment Company, Portfolio Turnover | 31% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ % Total number of portfolio holdings $ % Total advisory fees paid (in millions) $ % Portfolio turnover rate $ % |
| Holdings [Text Block] | Portfolio holdings by sector |
