| Form N-CSR Cover | 12 Months Ended |
| Aug. 31, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | AMERICAN FUNDS MORTGAGE FUND |
| Entity Central Index Key | 0001496998 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Aug. 31, 2024 |
| Shareholder Report | 12 Months Ended |
| Aug. 31, 2024 USD ($) Holding | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | AMERICAN FUNDS MORTGAGE FUND |
| Entity Central Index Key | 0001496998 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Aug. 31, 2024 |
| American Funds Mortgage Fund® - Class A [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class A |
| Trading Symbol | MFAAX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 0.71 % |
| Expenses Paid, Amount | $ 73 |
| Expense Ratio, Percent | 0.71% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class A shares gained 6.74% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-A What factors influenced results Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class A (with sales charge) * 2.75 % (0.46 ) % 0.86 % American Funds Mortgage Fund — Class A (without sales charge) * 6.74 % 0.30 % 1.25 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type erce *Includes derivatives. |
| American Funds Mortgage Fund® - Class R-6 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class R-6 |
| Trading Symbol | RMAGX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 0.26 % |
| Expenses Paid, Amount | $ 27 |
| Expense Ratio, Percent | 0.26% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-6 shares gained 7.21% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities Index. For information on returns for additional periods, including the fund lifetime, please refer to capitalgroup.com/mutual-fund-returns-R6 What factors influenced results Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class R-6 * 7.21 % 0.72 % 1.65 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class R-5E [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class R-5E |
| Trading Symbol | RMAHX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 0.44 % |
| Expenses Paid, Amount | $ 46 |
| Expense Ratio, Percent | 0.44% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-5E shares gained 7.03% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class R-5E 2 7.03 % 0.55 % 1.36 % Bloomberg U.S. Aggregate Index 3 7.30 % (0.04 ) % 1.66 % Bloomberg U.S. Mortgage Backed Securities Index 3 7.46 % (0.18 ) % 1.11 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fun Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class R-5 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class R-5 |
| Trading Symbol | RMAFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 0.33 % |
| Expenses Paid, Amount | $ 34 |
| Expense Ratio, Percent | 0.33% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-5 shares gained 7.02% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class R-5 * 7.02 % 0.66 % 1.58 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund®`- Class R-2 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class R-2 |
| Trading Symbol | RMABX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 1.36 % |
| Expenses Paid, Amount | $ 140 |
| Expense Ratio, Percent | 1.36% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-2 shares gained 5.95% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class R-2 * 5.95 % (0.40 ) % 0.50 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class R-2E [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class R-2E |
| Trading Symbol | RMBEX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class R-2E $ 1.06 % |
| Expenses Paid, Amount | $ 109 |
| Expense Ratio, Percent | 1.06% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-2E shares gained 6.38% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class R-2E * 6.38 % (0.07 ) % 0.97 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class R-3 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class R-3 |
| Trading Symbol | RMACX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 0.92 % |
| Expenses Paid, Amount | $ 95 |
| Expense Ratio, Percent | 0.92% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-3 shares gained 6.51% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class R-3 * 6.51 % 0.02 % 0.94 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class R-4 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class R-4 |
| Trading Symbol | RMAEX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 R-4 $ 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 R-4 shares gained 6.70% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class R-4 * 6.70 % 0.36 % 1.29 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class C [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class C |
| Trading Symbol | MFACX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 1.46 % |
| Expenses Paid, Amount | $ 150 |
| Expense Ratio, Percent | 1.46% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class C shares gained 5.85% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class C (with sales charge) * 4.85 % (0.44 ) % 0.62 % American Funds Mortgage Fund — Class C (without sales charge) * 5.85 % (0.44 ) % 0.62 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % 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. |
| Net Assets | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class T [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class T |
| Trading Symbol | TFMFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 0.46 % |
| Expenses Paid, Amount | $ 48 |
| Expense Ratio, Percent | 0.46% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class T shares gained 6.89% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities Index. What factors influenced results Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class T (with sales charge) 2 4.27 % 0.03 % 0.85 % American Funds Mortgage Fund — Class T (without sales charge) 2 6.89 % 0.54 % 1.19 % Bloomberg U.S. Aggregate Index 3 7.30 % (0.04 ) % 1.50 % Bloomberg U.S. Mortgage Backed Securities Index 3 7.46 % (0.18 ) % 0.99 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund®`- Class F-1 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class F-1 |
| Trading Symbol | MFAEX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class F-1 $ 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 F-1 shares gained 6.82% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class F-1 * 6.82 % 0.35 % 1.27 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class F-2 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class F-2 |
| Trading Symbol | MFAFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class F-2 $ 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 F-2 shares gained 6.97% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class F-2 * 6.97 % 0.59 % 1.54 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class F-3 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class F-3 |
| Trading Symbol | AFFMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 0.27 % |
| Expenses Paid, Amount | $ 28 |
| Expense Ratio, Percent | 0.27% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class F-3 shares gained 7.10% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class F-3 2 7.10 % 0.70 % 1.42 % Bloomberg U.S. Aggregate Index 3 7.30 % (0.04 ) % 1.58 % Bloomberg U.S. Mortgage Backed Securities Index 3 7.46 % (0.18 ) % 1.08 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. 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. |
| Net Assets | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class 529-A [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class 529-A |
| Trading Symbol | CMFAX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 0.73 % |
| Expenses Paid, Amount | $ 75 |
| Expense Ratio, Percent | 0.73% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-A shares gained 6.59% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class 529-A (with sales charge) * 2.83 % (0.46 ) % 0.83 % American Funds Mortgage Fund — Class 529-A (without sales charge) * 6.59 % 0.25 % 1.19 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * results † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class 529-C [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class 529-C |
| Trading Symbol | CMFCX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 1.50 % |
| Expenses Paid, Amount | $ 154 |
| Expense Ratio, Percent | 1.50% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-C shares gained 5.81% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class 529-C (with sales charge) * 4.81 % (0.49 ) % 0.79 % American Funds Mortgage Fund — Class 529-C (without sales charge) * 5.81 % (0.49 ) % 0.79 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class 529-E [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class 529-E |
| Trading Symbol | CMFEX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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? Share class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class 529-E $ 0.89 % |
| Expenses Paid, Amount | $ 92 |
| Expense Ratio, Percent | 0.89% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-E shares gained 6.43% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class 529-E * 6.43 % 0.07 % 0.98 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including transactions 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class 529-T [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class 529-T |
| Trading Symbol | TMFMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 0.51 % |
| Expenses Paid, Amount | $ 53 |
| Expense Ratio, Percent | 0.51% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-T shares gained 6.83% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities Index. What factors influenced results Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class 529-T (with sales charge) 2 4.21 % (0.03 ) % 0.79 % American Funds Mortgage Fund — Class 529-T (without sales charge) 2 6.83 % 0.48 % 1.14 % Bloomberg U.S. Aggregate Index 3 7.30 % (0.04 ) % 1.50 % Bloomberg U.S. Mortgage Backed Securities Index 3 7.46 % (0.18 ) % 0.99 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class 529-F-1 | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class 529-F-1 |
| Trading Symbol | CMFFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage Fund (the "fund") September 1, 2023 |
| 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 $ 0.42 % |
| 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-1 shares gained 7.04% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class 529-F-1 * 7.04 % 0.54 % 1.44 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class 529-F-2 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class 529-F-2 |
| Trading Symbol | FFMFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 |
| Material Fund Change Notice [Text Block] | This report describes changes to the fund that occurred during the reporting period. |
| 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 $ 0.43 % |
| 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-F-2 shares gained 6.91% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class 529-F-2 2 6.91 % (0.91 ) % Bloomberg U.S. Aggregate Index 3 7.30 % (1.54 ) % Bloomberg U.S. Mortgage Backed Securities Index 3 7.46 % (1.34 ) % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. 1 October 30, 2020 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. |
| Material Change Date | Sep. 01, 2023 |
| Net Assets | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| Material Fund Change [Text Block] | Material fund changes This is a summary of certain changes to the fund since September 1, 2023. For more complete information, you may review the fund’s next prospectus, which we expect to be available by November 1, 2024 at capitalgroup.com/mutual-fund-literature-529F2 The total annual operating expense ratio after expense waiver for Class 529-F-2 shares increased from 0.35% to 0.43% during the reporting period. |
| Material Fund Change Expenses [Text Block] | The total annual operating expense ratio after expense waiver for Class 529-F-2 shares increased from 0.35% to 0.43% during the reporting period. |
| Updated Prospectus Phone Number | (800) 421-4225 |
| Updated Prospectus Web Address | capitalgroup.com/mutual-fund-literature-529F2 |
| American Funds Mortgage Fund® - Class 529-F-3 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class 529-F-3 |
| Trading Symbol | FMMFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 0.30 % |
| Expenses Paid, Amount | $ 31 |
| Expense Ratio, Percent | 0.30% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class 529-F-3 shares gained 7.05% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class 529-F-3 2 7.05 % (0.81 ) % Bloomberg U.S. Aggregate Index 3 7.30 % (1.54 ) % Bloomberg U.S. Mortgage Backed Securities Index 3 7.46 % (1.34 ) % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. 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. |
| Net Assets | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| American Funds Mortgage Fund® - Class R-1 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | American Funds Mortgage Fund® |
| Class Name | Class R-1 |
| Trading Symbol | RMAAX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about American Funds Mortgage 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 $ 1.39 % |
| Expenses Paid, Amount | $ 143 |
| Expense Ratio, Percent | 1.39% |
| Factors Affecting Performance [Text Block] | Management's discussion of fund performance The fund’s Class R-1 shares gained 6.04% for the year ended August 31, 2024. That result compares with a 7.46% gain for the Bloomberg U.S. Mortgage Backed Securities 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 Expectations that the U.S. Federal Reserve would begin to cut the federal funds rate contributed to a notable decline in Treasury bond yields, which pushed bond prices higher. The Fed’s potential move comes as inflation cooled, hitting a three-year low in August, and hiring slowed. Mortgage rates continued to trend downwards, starting in May through the fund’s fiscal year-end, with the average rate on the 30-year mortgage hovering at around 6.2% in mid-September, according to Freddie Mac. Based on home sales, housing demand remained weak as buyers held off in anticipation of even lower rates. Security selection within mortgages was additive, with notable contributions from the fund’s larger positions in Federal National Mortgage Association and Federal Home Loan Mortgage. The fund's allocation to higher coupon mortgages was also additive. This was boosted further by smaller allocations to asset-backed securities and commercial mortgage-backed securities. Allocations to Treasuries, inflation-linked bonds and agency bonds were less additive as returns for those markets were outpaced by securitized markets. Interest rate positioning contributed to returns overall, aided by declining yields. In particular, the shorter end of the curve fell further than longer-term yields, which helped returns as the fund placed greater emphasis on shorter-term bonds over the period. |
| 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 Mortgage Fund — Class R-1 * 6.04 % (0.43 ) % 0.54 % Bloomberg U.S. Aggregate Index † 7.30 % (0.04 ) % 1.64 % Bloomberg U.S. Mortgage Backed Securities Index † 7.46 % (0.18 ) % 1.28 % Effective July 24, 2024, the fund's primary benchmark changed from the Bloomberg U.S. Mortgage Backed Securities Index (the "Previous Primary Benchmark") to the Bloomberg U.S. Aggregate Index, a broad-based index that represents the overall applicable securities market, as required by the SEC. The Previous Primary Benchmark provides a means to compare the fund's results to a benchmark that the investment adviser believes is more representative of the fund's investment universe. There is no change in the fund's investment strategies as a result of the benchmark change. * † |
| 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 | $ 11,046,000,000 |
| Holdings Count | Holding | 823 |
| Advisory Fees Paid, Amount | $ 23,000,000 |
| Investment Company, Portfolio Turnover | 824% |
| Additional Fund Statistics [Text Block] | Key fund statistics Fund net assets (in millions) $ Total number of portfolio holdings 823 Total advisory fees paid (in millions) $ Portfolio turnover rate including 824 % Portfolio turnover rate excluding mortgage dollar roll transactions 37 % |
| Holdings [Text Block] | Portfolio holdings by asset type *Includes derivatives. |
| Shareholder Report, Line Graph (Details) - USD ($) | 12 Months Ended | |||||||||||||||||||
| Aug. 31, 2024 | Feb. 29, 2024 | Aug. 31, 2023 | Feb. 28, 2023 | Aug. 31, 2022 | Feb. 28, 2022 | Aug. 31, 2021 | Feb. 28, 2021 | Oct. 30, 2020 | Aug. 31, 2020 | Aug. 31, 2019 | Aug. 31, 2018 | Aug. 31, 2017 | Apr. 07, 2017 | Jan. 27, 2017 | Aug. 31, 2016 | Nov. 20, 2015 | Aug. 31, 2015 | Aug. 31, 2014 | ||
| American Funds Mortgage Fund® - Class R-1 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class R-1 | ||||||||||||||||||
| Account Value | $ 10,550 | $ 9,949 | $ 10,344 | $ 11,292 | $ 11,357 | $ 10,782 | $ 10,239 | $ 10,510 | $ 10,392 | $ 10,161 | $ 10,000 | |||||||||
| American Funds Mortgage Fund® - Class 529-F-3 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class 529-F-3 | ||||||||||||||||||
| Account Value | $ 9,693 | $ 9,216 | 9,055 | $ 9,050 | 9,306 | $ 9,872 | 10,050 | $ 9,974 | $ 10,000 | |||||||||||
| American Funds Mortgage Fund® - Class 529-F-2 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class 529-F-2 | ||||||||||||||||||
| Account Value | $ 9,657 | $ 9,188 | 9,033 | $ 9,028 | 9,287 | $ 9,856 | 10,039 | $ 9,970 | 10,000 | |||||||||||
| American Funds Mortgage Fund® - Class 529-F-1 | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-F-1 | |||||||||||||||||||
| Account Value | $ 11,539 | 10,780 | 11,094 | 12,009 | 11,957 | 11,235 | 10,576 | 10,754 | 10,532 | 10,222 | 10,000 | |||||||||
| American Funds Mortgage Fund® - Class 529-T [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-T (with sales charge) | |||||||||||||||||||
| Account Value | $ 10,600 | 9,922 | 10,214 | 11,047 | 11,013 | 10,350 | 9,733 | 9,905 | $ 9,749 | |||||||||||
| American Funds Mortgage Fund® - Class 529-E [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-E | |||||||||||||||||||
| Account Value | $ 11,024 | 10,358 | 10,711 | 11,629 | 11,640 | 10,985 | 10,386 | 10,608 | 10,436 | 10,165 | 10,000 | |||||||||
| American Funds Mortgage Fund® - Class 529-C [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-C (with sales charge) | |||||||||||||||||||
| Account Value | $ 10,821 | 10,152 | 10,477 | 11,357 | 11,345 | 10,685 | 10,155 | 10,429 | 10,316 | 10,110 | 10,000 | |||||||||
| American Funds Mortgage Fund® - Class 529-A [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-A (with sales charge) | |||||||||||||||||||
| Account Value | $ 10,860 | 10,188 | 10,515 | 11,398 | 11,386 | 10,723 | 10,107 | 10,312 | 10,111 | 9,834 | 9,650 | |||||||||
| American Funds Mortgage Fund® - Class F-3 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class F-3 | ||||||||||||||||||
| Account Value | $ 11,131 | 10,393 | 10,675 | 11,522 | 11,461 | 10,748 | 10,086 | 10,233 | $ 10,000 | |||||||||||
| American Funds Mortgage Fund® - Class F-2 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class F-2 | |||||||||||||||||||
| Account Value | $ 11,651 | 10,892 | 11,201 | 12,103 | 12,052 | 11,315 | 10,628 | 10,805 | 10,562 | 10,237 | 10,000 | |||||||||
| American Funds Mortgage Fund®`- Class F-1 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class F-1 | |||||||||||||||||||
| Account Value | $ 11,342 | 10,618 | 10,959 | 11,873 | 11,855 | 11,148 | 10,511 | 10,707 | 10,505 | 10,208 | 10,000 | |||||||||
| American Funds Mortgage Fund® - Class T [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class T (with sales charge) | |||||||||||||||||||
| Account Value | $ 10,645 | 9,958 | 10,242 | 11,072 | 11,033 | 10,364 | 9,741 | 9,908 | 9,749 | |||||||||||
| American Funds Mortgage Fund® - Class C [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class C (with sales charge) | |||||||||||||||||||
| Account Value | $ 10,639 | 9,967 | 10,284 | 11,229 | 11,304 | 10,710 | 10,175 | 10,456 | 10,327 | 10,114 | 10,000 | |||||||||
| American Funds Mortgage Fund® - Class R-4 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class R-4 | |||||||||||||||||||
| Account Value | $ 11,371 | 10,657 | 10,987 | 11,899 | 11,877 | 11,168 | 10,527 | 10,720 | 10,516 | 10,216 | 10,000 | |||||||||
| American Funds Mortgage Fund® - Class R-3 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class R-3 | ||||||||||||||||||
| Account Value | $ 10,976 | 10,305 | 10,659 | 11,589 | 11,602 | 10,964 | 10,368 | 10,595 | 10,429 | 10,168 | 10,000 | |||||||||
| American Funds Mortgage Fund® - Class R-2E [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class R-2E | ||||||||||||||||||
| Account Value | $ 11,011 | 10,351 | 10,718 | 11,661 | 11,694 | 11,051 | 10,451 | 10,697 | 10,520 | 10,222 | 10,000 | |||||||||
| American Funds Mortgage Fund®`- Class R-2 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class R-2 | ||||||||||||||||||
| Account Value | $ 10,509 | 9,919 | 10,298 | 11,242 | 11,306 | 10,720 | 10,177 | 10,442 | 10,320 | 10,108 | 10,000 | |||||||||
| American Funds Mortgage Fund® - Class R-5 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class R-5 | |||||||||||||||||||
| Account Value | $ 11,699 | 10,932 | 11,237 | 12,135 | 12,078 | 11,323 | 10,642 | 10,804 | 10,566 | 10,240 | 10,000 | |||||||||
| American Funds Mortgage Fund® - Class R-5E [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class R-5E | |||||||||||||||||||
| Account Value | $ 11,264 | 10,525 | 10,829 | 11,707 | 11,664 | 10,957 | 10,309 | 10,469 | 10,239 | $ 10,000 | ||||||||||
| American Funds Mortgage Fund® - Class R-6 [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class R-6 | |||||||||||||||||||
| Account Value | $ 11,781 | 10,988 | 11,300 | 12,196 | 12,131 | 11,364 | 10,674 | 10,830 | 10,583 | 10,248 | 10,000 | |||||||||
| American Funds Mortgage Fund® - Class A [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class A (with sales charge) | |||||||||||||||||||
| Account Value | $ 10,895 | 10,207 | 10,531 | 11,424 | 11,409 | 10,731 | 10,119 | 10,305 | 10,109 | 9,824 | 9,623 | |||||||||
| Bloomberg US Aggregate Index [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | Bloomberg U.S. Aggregate Index | |||||||||||||||||||
| Account Value | $ 11,765 | 10,965 | 11,098 | 12,542 | 10,000 | 12,553 | 11,789 | 10,701 | 10,814 | 10,000 | 10,000 | 10,761 | 10,000 | 10,156 | 10,000 | |||||
| Bloomberg U.S. Mortgage Backed Securities Index [Member] | ||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||
| Line Graph and Table Measure Name | Bloomberg U.S. Mortgage Backed Securities Index | |||||||||||||||||||
| Account Value | $ 11,352 | $ 10,564 | $ 10,790 | $ 11,953 | $ 10,000 | $ 11,974 | $ 11,454 | $ 10,698 | $ 10,756 | $ 10,000 | $ 10,000 | $ 10,670 | $ 10,000 | $ 10,266 | $ 10,000 | |||||
| [1]Investment results assume all distributions are reinvested and reflect applicable fees and expenses. When applicable, results reflect fee waivers and/or expense reimbursements, without which they would have been lower. | ||||||||||||||||||||
| Shareholder Report, Average Annual Return (Details) | 12 Months Ended | 46 Months Ended | 60 Months Ended | 89 Months Ended | 91 Months Ended | 105 Months Ended | 120 Months Ended | |||||
| Aug. 31, 2024 | Aug. 31, 2024 | Aug. 31, 2024 | Aug. 31, 2024 | Aug. 31, 2024 | Aug. 31, 2024 | [7] | Aug. 31, 2024 | |||||
| American Funds Mortgage Fund® - Class R-1 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class R-1 | ||||||||||
| Average Annual Return, Percent | [1] | 6.04% | (0.43%) | 0.54% | ||||||||
| American Funds Mortgage Fund® - Class 529-F-3 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class 529-F-3 | ||||||||||
| Average Annual Return, Percent | [1] | 7.05% | (0.81%) | [2] | ||||||||
| American Funds Mortgage Fund® - Class 529-F-2 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class 529-F-2 | ||||||||||
| Average Annual Return, Percent | [1] | 6.91% | (0.91%) | [3] | ||||||||
| American Funds Mortgage Fund® - Class 529-F-1 | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-F-1 | |||||||||||
| Average Annual Return, Percent | [1] | 7.04% | 0.54% | 1.44% | ||||||||
| American Funds Mortgage Fund® - Class 529-T [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-T (with sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 4.21% | (0.03%) | 0.79% | [4] | |||||||
| American Funds Mortgage Fund® - Class 529-E [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-E | |||||||||||
| Average Annual Return, Percent | [1] | 6.43% | 0.07% | 0.98% | ||||||||
| American Funds Mortgage Fund® - Class 529-C [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-C (with sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 4.81% | (0.49%) | 0.79% | ||||||||
| American Funds Mortgage Fund® - Class 529-A [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-A (with sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 2.83% | (0.46%) | 0.83% | ||||||||
| American Funds Mortgage Fund® - Class F-3 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class F-3 | ||||||||||
| Average Annual Return, Percent | [1],[5] | 7.10% | 0.70% | 1.42% | ||||||||
| American Funds Mortgage Fund® - Class F-2 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class F-2 | |||||||||||
| Average Annual Return, Percent | [1] | 6.97% | 0.59% | 1.54% | ||||||||
| American Funds Mortgage Fund®`- Class F-1 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class F-1 | |||||||||||
| Average Annual Return, Percent | [1] | 6.82% | 0.35% | 1.27% | ||||||||
| American Funds Mortgage Fund® - Class T [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class T (with sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 4.27% | 0.03% | 0.85% | [6] | |||||||
| American Funds Mortgage Fund® - Class C [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class C (with sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 4.85% | (0.44%) | 0.62% | ||||||||
| American Funds Mortgage Fund® - Class R-4 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class R-4 | |||||||||||
| Average Annual Return, Percent | [1] | 6.70% | 0.36% | 1.29% | ||||||||
| American Funds Mortgage Fund® - Class R-3 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class R-3 | ||||||||||
| Average Annual Return, Percent | [1] | 6.51% | 0.02% | 0.94% | ||||||||
| American Funds Mortgage Fund® - Class R-2E [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class R-2E | ||||||||||
| Average Annual Return, Percent | [1] | 6.38% | (0.07%) | 0.97% | ||||||||
| American Funds Mortgage Fund®`- Class R-2 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | [1] | American Funds Mortgage Fund — Class R-2 | ||||||||||
| Average Annual Return, Percent | [1] | 5.95% | (0.40%) | 0.50% | ||||||||
| American Funds Mortgage Fund® - Class R-5 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class R-5 | |||||||||||
| Average Annual Return, Percent | [1] | 7.02% | 0.66% | 1.58% | ||||||||
| American Funds Mortgage Fund® - Class R-5E [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class R-5E | |||||||||||
| Average Annual Return, Percent | [1] | 7.03% | 0.55% | 1.36% | ||||||||
| American Funds Mortgage Fund® - Class R-6 [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class R-6 | |||||||||||
| Average Annual Return, Percent | [1] | 7.21% | 0.72% | 1.65% | ||||||||
| American Funds Mortgage Fund® - Class A [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class A (with sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 2.75% | (0.46%) | 0.86% | ||||||||
| Without Sales Load [Member] | American Funds Mortgage Fund® - Class 529-T [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-T (without sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 6.83% | 0.48% | 1.14% | [4] | |||||||
| Without Sales Load [Member] | American Funds Mortgage Fund® - Class 529-C [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-C (without sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 5.81% | (0.49%) | 0.79% | ||||||||
| Without Sales Load [Member] | American Funds Mortgage Fund® - Class 529-A [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class 529-A (without sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 6.59% | 0.25% | 1.19% | ||||||||
| Without Sales Load [Member] | American Funds Mortgage Fund® - Class T [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class T (without sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 6.89% | 0.54% | 1.19% | [6] | |||||||
| Without Sales Load [Member] | American Funds Mortgage Fund® - Class C [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class C (without sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 5.85% | (0.44%) | 0.62% | ||||||||
| Without Sales Load [Member] | American Funds Mortgage Fund® - Class A [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | American Funds Mortgage Fund — Class A (without sales charge) | |||||||||||
| Average Annual Return, Percent | [1] | 6.74% | 0.30% | 1.25% | ||||||||
| Bloomberg U.S. Aggregate Index [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg U.S. Aggregate Index | |||||||||||
| Average Annual Return, Percent | [8] | 7.30% | (1.54%) | [2],[3] | (0.04%) | 1.50% | [4],[6] | 1.58% | [5] | 1.66% | 1.64% | |
| Bloomberg U.S. Mortgage Backed Securities Index [Member] | ||||||||||||
| Average Annual Return [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg U.S. Mortgage Backed Securities Index | |||||||||||
| Average Annual Return, Percent | [8] | 7.46% | (1.34%) | [2],[3] | (0.18%) | 0.99% | [4],[6] | 1.08% | [5] | 1.11% | 1.28% | |
| [1]Investment results assume all distributions are reinvested and reflect applicable fees and expenses. When applicable, results reflect fee waivers and/or expense reimbursements, without which they would have been lower.[2]Class 529-F-3 shares were first offered on October 30, 2020.[3]Class 529-F-2 shares were first offered on October 30, 2020.[4]Class 529-T shares were first offered on April 7, 2017.[5]Class F-3 shares were first offered on January 27, 2017.[6]Class T shares were first offered on April 7, 2017.[7]Class R-5E shares were first offered on November 20, 2015.[8]Results assume all distributions are reinvested. Any market index shown is unmanaged, and therefore, has no expenses. Investors cannot invest directly in an index. Source(s): Bloomberg Index Services Ltd. | ||||||||||||
| Shareholder Report, Holdings (Details) | Aug. 31, 2024 | |
| American Funds Mortgage Fund® - Class A [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class A [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class A [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class A [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class A [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class R-6 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class R-6 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class R-6 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class R-6 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class R-6 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class R-5E [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class R-5E [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class R-5E [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class R-5E [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class R-5E [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class R-5 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class R-5 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class R-5 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class R-5 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class R-5 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund®`- Class R-2 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund®`- Class R-2 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund®`- Class R-2 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund®`- Class R-2 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund®`- Class R-2 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class R-2E [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class R-2E [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class R-2E [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class R-2E [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class R-2E [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class R-3 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class R-3 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class R-3 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class R-3 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class R-3 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class R-4 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class R-4 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class R-4 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class R-4 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class R-4 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class C [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class C [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class C [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class C [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class C [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class T [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class T [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class T [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class T [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class T [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund®`- Class F-1 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund®`- Class F-1 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund®`- Class F-1 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund®`- Class F-1 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund®`- Class F-1 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class F-2 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class F-2 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class F-2 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class F-2 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class F-2 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class F-3 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class F-3 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class F-3 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class F-3 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class F-3 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class 529-A [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class 529-A [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class 529-A [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class 529-A [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class 529-A [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class 529-C [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class 529-C [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class 529-C [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class 529-C [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class 529-C [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class 529-E [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class 529-E [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class 529-E [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class 529-E [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class 529-E [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class 529-T [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class 529-T [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class 529-T [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class 529-T [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class 529-T [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class 529-F-1 | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class 529-F-1 | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class 529-F-1 | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class 529-F-1 | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class 529-F-1 | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class 529-F-2 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class 529-F-2 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class 529-F-2 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class 529-F-2 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class 529-F-2 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class 529-F-3 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class 529-F-3 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class 529-F-3 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class 529-F-3 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class 529-F-3 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| American Funds Mortgage Fund® - Class R-1 [Member] | Mortgage-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 82.06% | |
| American Funds Mortgage Fund® - Class R-1 [Member] | U.S. Treasury bonds & notes [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.72% | |
| American Funds Mortgage Fund® - Class R-1 [Member] | Asset-backed obligations [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.08% | |
| American Funds Mortgage Fund® - Class R-1 [Member] | Options purchased [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.01% | |
| American Funds Mortgage Fund® - Class R-1 [Member] | Short-term securities and other assets less liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.13% | [1] |
| [1]Includes derivatives. | ||
