| Form N-CSR Cover | 6 Months Ended |
| May 31, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | General Municipal Money Market Funds, Inc. |
| Entity Central Index Key | 0000703153 |
| Document Period End Date | May 31, 2024 |
| Shareholder Report | 6 Months Ended |
| May 31, 2024 USD ($) | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | General Municipal Money Market Funds, Inc. |
| Entity Central Index Key | 0000703153 |
| Document Period End Date | May 31, 2024 |
| Wealth Shares | |
| Shareholder Report [Line Items] | |
| Fund Name | Dreyfus National Municipal Money Market Fund |
| Class Name | Wealth Shares |
| Trading Symbol | GTMXX |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Service Shares | |
| Shareholder Report [Line Items] | |
| Fund Name | Dreyfus National Municipal Money Market Fund |
| Class Name | Service Shares |
| Trading Symbol | GBMXX |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Premier Shares | |
| Shareholder Report [Line Items] | |
| Fund Name | Dreyfus National Municipal Money Market Fund |
| Class Name | Premier Shares |
| Trading Symbol | GMHXX |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| General Municipal Money Market Funds, Inc. | Wealth Shares | |
| Shareholder Report [Line Items] | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Dreyfus National Municipal Money Market Fund (the “Fund”) for the period of December 1, 2023 to May 31, 2024. You can find additional information about the Fund at www.dreyfus.com/products/mm.html#overview. You can also request this information by calling 1-800-373-9387 (inside the U.S. only) or by sending an e-mail request to info bnymellon.com. |
| Additional Information [Text Block] | You can find additional information about the Fund at www.dreyfus.com/products/mm.html#overview. You can also request this information by calling 1-800-373-9387 (inside the U.S. only) or by sending an e-mail request to info bnymellon.com. |
| Additional Information Phone Number | 1-800-373-9387 |
| Additional Information Email | info@bnymellon.com |
| Additional Information Website | www.dreyfus.com/products/mm.html#overview |
| Expenses [Text Block] | What were the Fund’s costs for the last six months? (based on a hypothetical $10,000 investment) Share Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Wealth Shares $51 0.51% |
| Expenses Paid, Amount | $ 51 |
| Expense Ratio, Percent | 0.51% |
| Net Assets | $ 663,000,000 |
| Holdings Count | 144 |
| Additional Fund Statistics [Text Block] | KEY FUND STATISTICS (AS OF 5/31/24) Fund Size (Millions) Number of Holdings $663 144 |
| Holdings [Text Block] | Portfolio Holdings (as of 5/31/24) Sector Allocation (Based on Net Assets) |
| Updated Prospectus Web Address | www.dreyfus.com/products/mm.html#overview |
| General Municipal Money Market Funds, Inc. | Service Shares | |
| Shareholder Report [Line Items] | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Dreyfus National Municipal Money Market Fund (the “Fund”) for the period of December 1, 2023 to May 31, 2024. You can find additional information about the Fund at www.dreyfus.com/products/mm.html#overview. You can also request this information by calling 1-800-373-9387 (inside the U.S. only) or by sending an e-mail request to info bnymellon.com. |
| Additional Information [Text Block] | You can find additional information about the Fund at www.dreyfus.com/products/mm.html#overview. You can also request this information by calling 1-800-373-9387 (inside the U.S. only) or by sending an e-mail request to info bnymellon.com. |
| Additional Information Phone Number | 1-800-373-9387 |
| Additional Information Email | info@bnymellon.com |
| Additional Information Website | www.dreyfus.com/products/mm.html#overview |
| Expenses [Text Block] | What were the Fund’s costs for the last six months? (based on a hypothetical $10,000 investment) Share Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Service Shares * $99 0.99% * During the period, fees were waived and/or expenses reimbursed pursuant to an agreement with the Fund’s investment adviser, BNY Mellon Investment Adviser, Inc. If this agreement is not extended in the future, expenses could be higher. |
| Expenses Paid, Amount | $ 99 |
| Expense Ratio, Percent | 0.99% |
| Net Assets | $ 663,000,000 |
| Holdings Count | 144 |
| Additional Fund Statistics [Text Block] | KEY FUND STATISTICS (AS OF 5/31/24) Fund Size (Millions) Number of Holdings $663 144 |
| Holdings [Text Block] | Portfolio Holdings (as of 5/31/24) Sector Allocation (Based on Net Assets) |
| Updated Prospectus Web Address | www.dreyfus.com/products/mm.html#overview |
| General Municipal Money Market Funds, Inc. | Premier Shares | |
| Shareholder Report [Line Items] | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Dreyfus National Municipal Money Market Fund (the “Fund”) for the period of December 1, 2023 to May 31, 2024. You can find additional information about the Fund at www.dreyfus.com/products/mm.html#overview. You can also request this information by calling 1-800-373-9387 (inside the U.S. only) or by sending an e-mail request to info bnymellon.com. |
| Additional Information [Text Block] | You can find additional information about the Fund at www.dreyfus.com/products/mm.html#overview. You can also request this information by calling 1-800-373-9387 (inside the U.S. only) or by sending an e-mail request to info bnymellon.com. |
| Additional Information Phone Number | 1-800-373-9387 |
| Additional Information Email | info@bnymellon.com |
| Additional Information Website | www.dreyfus.com/products/mm.html#overview |
| Expenses [Text Block] | What were the Fund’s costs for the last six months? (based on a hypothetical $10,000 investment) Share Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Premier Shares $30 0.30% |
| Expenses Paid, Amount | $ 30 |
| Expense Ratio, Percent | 0.30% |
| Net Assets | $ 663,000,000 |
| Holdings Count | 144 |
| Additional Fund Statistics [Text Block] | KEY FUND STATISTICS (AS OF 5/31/24) Fund Size (Millions) Number of Holdings $663 144 |
| Holdings [Text Block] | Portfolio Holdings (as of 5/31/24) Sector Allocation (Based on Net Assets) |
| Updated Prospectus Web Address | www.dreyfus.com/products/mm.html#overview |
| Shareholder Report, Holdings (Details) - General Municipal Money Market Funds, Inc. | May 31, 2024 |
| Wealth Shares | Other | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.20% |
| Wealth Shares | Water | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Wealth Shares | Transportation | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2% |
| Wealth Shares | Housing | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3% |
| Wealth Shares | Electric | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.10% |
| Wealth Shares | Pollution | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Wealth Shares | Medical | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.10% |
| Wealth Shares | Education | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.90% |
| Wealth Shares | Nursing Homes | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.50% |
| Wealth Shares | School District | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.70% |
| Wealth Shares | Development | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.20% |
| Wealth Shares | Airport | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.70% |
| Wealth Shares | General Obligation | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.80% |
| Wealth Shares | Multifamily Housing | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16.10% |
| Service Shares | Other | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.20% |
| Service Shares | Water | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Service Shares | Transportation | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2% |
| Service Shares | Housing | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3% |
| Service Shares | Electric | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.10% |
| Service Shares | Pollution | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Service Shares | Medical | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.10% |
| Service Shares | Education | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.90% |
| Service Shares | Nursing Homes | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.50% |
| Service Shares | School District | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.70% |
| Service Shares | Development | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.20% |
| Service Shares | Airport | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.70% |
| Service Shares | General Obligation | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.80% |
| Service Shares | Multifamily Housing | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16.10% |
| Premier Shares | Other | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.20% |
| Premier Shares | Water | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Premier Shares | Transportation | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2% |
| Premier Shares | Housing | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3% |
| Premier Shares | Electric | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.10% |
| Premier Shares | Pollution | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Premier Shares | Medical | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.10% |
| Premier Shares | Education | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.90% |
| Premier Shares | Nursing Homes | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.50% |
| Premier Shares | School District | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.70% |
| Premier Shares | Development | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.20% |
| Premier Shares | Airport | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.70% |
| Premier Shares | General Obligation | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.80% |
| Premier Shares | Multifamily Housing | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16.10% |
