| Shareholder Report | 12 Months Ended |
| Sep. 30, 2024 USD ($) Holding |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | American Funds U.S. Government Money Market Fund |
| Entity Central Index Key | 0001454975 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Sep. 30, 2024 |
| American Funds® U.S. Government Money Market Fund - Class A | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class A |
| Trading Symbol | AFAXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.51 % |
| Expenses Paid, Amount | $ 52 |
| Expense Ratio, Percent | 0.51% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class A shares gained 4.98% for the year ended September 30, 2024. That result co mp capitalgroup.com/mutual-fund-returns-A What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields |
| 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 to tal 1 year 5 years 10 years American Funds U.S. Government Money Market Fund — Class A * 4.98 % 2.05 % 1.37 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was u pd * † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was u pd |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Tre asur 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class C | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class C |
| Trading Symbol | AFCXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.63 % |
| Expenses Paid, Amount | $ 65 |
| Expense Ratio, Percent | 0.63% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class C shares gained 4.86% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-C What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained |
| 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 Funds U.S. Government Money Market Fund — Class C (with sales charge) * 3.86 % 2.00 % 1.36 % American Funds U.S. Government Money Market Fund — Class C (without sales charge)* 4.86 % 2.00 % 1.36 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * or † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class T | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class T |
| Trading Symbol | TTMXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.37 % |
| Expenses Paid, Amount | $ 38 |
| Expense Ratio, Percent | 0.37% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class T shares gained 5.13% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year |
| 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 Funds U.S. Government Money Market Fund — Class T 2 5.13 % 2.11 % 1.86 % USTREAS T-Bill Auction Ave 3 Mon 3 5.53 % 2.48 % 2.27 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. 1 2 applicable 3 reinvested |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class F-1 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class F-1 |
| Trading Symbol | AFFXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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? investment Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class F-1 $ 0.66 % |
| Expenses Paid, Amount | $ 68 |
| Expense Ratio, Percent | 0.66% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class F-1 shares gained 4.82% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-F1 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class F-1 * 4.82 % 1.92 % 1.22 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * † |
| No Deduction of Taxes [Text Block] | The line chart and |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class F-2 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class F-2 |
| Trading Symbol | AFGXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 based on a hypothetical $10,000 investment) 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 | $ 39 |
| Expense Ratio, Percent | 0.38% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class F-2 shares gained 5.12% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-F2 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class F-2 * 5.12 % 2.10 % 1.38 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class F-3 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class F-3 |
| Trading Symbol | USGXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.31 % |
| Expenses Paid, Amount | $ 32 |
| Expense Ratio, Percent | 0.31% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class F-3 shares gained 5.19% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-F3 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings |
| 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 Funds U.S. Government Money Market Fund — Class F-3 2 5.19 % 2.14 % 1.85 % USTREAS T-Bill Auction Ave 3 Mon 3 5.53 % 2.48 % 2.23 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. 1 2 3 |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class 529-A | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class 529-A |
| Trading Symbol | AAFXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.56 % |
| Expenses Paid, Amount | $ 57 |
| Expense Ratio, Percent | 0.56% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-A shares gained 4.93% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529A What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high |
| 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 Funds U.S. Government Money Market Fund — Class 529-A * 4.93 % 2.01 % 1.32 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction * † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type percent Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class 529-C | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class 529-C |
| Trading Symbol | CCFXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.68 % |
| Expenses Paid, Amount | $ 70 |
| Expense Ratio, Percent | 0.68% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-C shares gained 4.80% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529C What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class 529-C (with sales charge) * 3.80 % 1.97 % 1.32 % American Funds U.S. Government Money Market Fund — Class 529-C (without sales charge) * 4.80 % 1.97 % 1.32 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class 529-E | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class 529-E |
| Trading Symbol | EAFXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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? hypothetical 10,000 investment Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class 529-E $ 0.67 % |
| Expenses Paid, Amount | $ 69 |
| Expense Ratio, Percent | 0.67% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-E shares gained 4.82% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529E What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class 529-E * 4.82 % 1.98 % 1.31 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * When † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class 529-T | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class 529-T |
| Trading Symbol | TSIXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.43 % |
| Expenses Paid, Amount | $ 44 |
| Expense Ratio, Percent | 0.43% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-T shares gained 5.06% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class 529-T 2 5.06 % 2.06 % 1.80 % USTREAS T-Bill Auction Ave 3 Mon 3 5.53 % 2.48 % 2.27 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class 529-F-1 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class 529-F-1 |
| Trading Symbol | FARXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.49 % |
| Expenses Paid, Amount | $ 50 |
| Expense Ratio, Percent | 0.49% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-F-1 shares gained 5.00% for the year ended September 30, 2024. That result compares with a 5.53% gain capitalgroup.com/mutual-fund-returns-529F1 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class 529-F-1 * 5.00 % 2.03 % 1.33 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * † and |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class 529-F-2 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class 529-F-2 |
| Trading Symbol | FFFXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.42 % |
| Expenses Paid, Amount | $ 43 |
| Expense Ratio, Percent | 0.42% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-F-2 shares gained 5.07% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529F2 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class 529-F-2 2 5.07 % 2.50 % USTREAS T-Bill Auction Ave 3 Mon 3 5.53 % 2.97 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a 1 2 3 cannot |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class 529-F-3 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class 529-F-3 |
| Trading Symbol | FMUXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class 529-F-3 $ 0.36 % |
| Expenses Paid, Amount | $ 37 |
| Expense Ratio, Percent | 0.36% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-F-3 shares gained 5.13% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-529F3 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class 529-F-3 2 5.13 % 2.52 % USTREAS T-Bill Auction Ave 3 Mon 3 5.53 % 2.97 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class ABLE-A | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class ABLE-A |
| Trading Symbol | AAZXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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-ABLEA |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-ABLEA |
| 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 ABLE-A $ 0.48 % |
| Expenses Paid, Amount | $ 49 |
| Expense Ratio, Percent | 0.48% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class ABLE-A shares gained 5.02% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-ABLEA What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class ABLE-A 2 5.02 % 2.06 % 2.03 % USTREAS T-Bill Auction Ave 3 Mon 3 5.53 % 2.48 % 2.45 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. 1 2 3 |
| Performance Inception Date | Jul. 13, 2018 |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class ABLE-F-2 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class ABLE-F-2 |
| Trading Symbol | ABZXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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-ABLEF2 |
| Additional Information Phone Number | (800) 421-4225 |
| Additional Information Website | capitalgroup.com/mutual-fund-literature-ABLEF2 |
| Expenses [Text Block] | What were the fund costs for the last year? stm Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class ABLE-F-2 $ 0.36 % |
| Expenses Paid, Amount | $ 37 |
| Expense Ratio, Percent | 0.36% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class ABLE-F-2 shares gained 5.14% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-ABLEF2 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class ABLE-F-2 2 5.14 % 2.54 % USTREAS T-Bill Auction Ave 3 Mon 3 5.53 % 2.97 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. 1 2 3 |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class R-1 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class R-1 |
| Trading Symbol | RAAXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.37 % |
| Expenses Paid, Amount | $ 38 |
| Expense Ratio, Percent | 0.37% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-1 shares gained 5.12% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R1 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money M ar * 5.12 % 2.09 % 1.37 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class R-2 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class R-2 |
| Trading Symbol | RABXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-2 $ 1.39 % |
| Expenses Paid, Amount | $ 142 |
| Expense Ratio, Percent | 1.39% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-2 shares gained 4.06% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R2 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 a 1 year 5 years 10 years American Funds U.S. Government Money Market Fund — Class R-2* 4.06 % 1.51 % 0.86 % USTREAS T-Bill Auction Ave 3 Mon† 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class R-2E | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class R-2E |
| Trading Symbol | RBEXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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? 10,000 Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-2E $ 1.11 % |
| Expenses Paid, Amount | $ 113 |
| Expense Ratio, Percent | 1.11% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-2E shares gained 4.36% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R2E What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class R-2E * 4.36 % 1.67 % 1.00 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class R-3 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class R-3 |
| Trading Symbol | RACXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.95 % |
| Expenses Paid, Amount | $ 97 |
| Expense Ratio, Percent | 0.95% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-3 capitalgroup.com/mutual-fund-returns-R3 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 A merican Funds U.S. Government Money Market Fund — Class R-3 * 4.52 % 1.76 % 1.07 % U STREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024 * † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024 |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class R-4 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class R-4 |
| Trading Symbol | RADXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.66 % |
| Expenses Paid, Amount | $ 68 |
| Expense Ratio, Percent | 0.66% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-4 shares gained 4.83% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R4 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class R-4 * 4.83 % 1.93 % 1.23 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * applicable † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class R-5E | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class R-5E |
| Trading Symbol | RAGXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.45 % |
| Expenses Paid, Amount | $ 46 |
| Expense Ratio, Percent | 0.45% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-5E shares gained 5.04% for the year ended September 30, 2024. That result compares with a 5.53% gain for t he to capitalgroup.com/mutual-fund-returns-R5E What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in |
| 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 Funds U.S. Government Money Market Fund — Class R-5E 2 5.04 % 2.05 % 1.51 % USTREAS T-Bill Auction Ave 3 Mon 3 5.53 % 2.48 % 1.97 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. 1 2 or 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 rede mp share |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class R-5 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class R-5 |
| Trading Symbol | RAEXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.36 % |
| Expenses Paid, Amount | $ 37 |
| Expense Ratio, Percent | 0.36% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-5 shares gained 5.14% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R5 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class R-5 * 5.14 % 2.11 % 1.39 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
| American Funds® U.S. Government Money Market Fund - Class R-6 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds® U.S. Government Money Market Fund |
| Class Name | Class R-6 |
| Trading Symbol | RAFXX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds U.S. Government Money Market Fund (the "fund") |
| 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 $ 0.31 % |
| Expenses Paid, Amount | $ 32 |
| Expense Ratio, Percent | 0.31% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-6 shares gained 5.19% for the year ended September 30, 2024. That result compares with a 5.53% gain for the USTREAS T-Bill Auction Ave 3 Mon. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R6 What factors influenced results U.S. bond markets remained strong during the fund’s fiscal year, most of which was spent in anticipation of a rate cut from the U.S. Federal Reserve that came at the tail end of the period. Commercial paper issuance remained strong. As can be expected, the bulk of the fund’s holdings are in commercial paper and other short-term instruments. Due to the high rate environment over the course of the fund’s fiscal year, yields remained steady for much of the time. The fund also had a small position in short-term U.S. Treasury securities. |
| 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 Funds U.S. Government Money Market Fund — Class R-6 * 5.19 % 2.14 % 1.43 % USTREAS T-Bill Auction Ave 3 Mon † 5.53 % 2.48 % 1.75 % Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. * † |
| 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. |
| Performance Table Market Index Changed [Text Block] | Effective July 24, 2024, the fund's primary benchmark was updated to USTREAS T-Bill Auction Ave 3 Mon, a broad-based index that represents the overall applicable securities market, as required by the SEC. There is no change in the fund's investment strategies as a result of the benchmark update. |
| Net Assets | $ 33,208,000,000 |
| Holdings Count | Holding | 138 |
| Advisory Fees Paid, Amount | $ 83,000,000 |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 138 Total advisory fees paid (in millions) $ |
| Holdings [Text Block] | Portfolio holdings by asset type Short-term securities: U.S. Treasury bills 58.05 % Federal agency bills & notes 23.61 % Repurchase agreements 13.10 % Bonds, notes & other debt instruments: U.S. Treasury bonds & notes 6.67 % Other assets less liabilities (1.43 ) % Total 100.00 % |
