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INCOME TAXES - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Income Tax Disclosure [Line Items] |  |  |
Deferred income tax assets | $ 7,593 | $ 7,886 |
State investment tax credit carryforward | 515 |  |
Operating loss carryforwards, valuation allowance | 82 |  |
Southern Power |  |  |
Income Tax Disclosure [Line Items] |  |  |
Deferred income tax assets | $ 638 | 773 |
Percentage reduction in tax basis of assets | 50.00% |  |
Operating loss carryforwards, valuation allowance | $ 21 |  |
Proceeds From Tax Credit Transfer | 24 |  |
Southern Power | ITCs and other credits carryforward |  |  |
Income Tax Disclosure [Line Items] |  |  |
Reduction in income tax expense, investment tax credits | 71 | 332 | $ 49
Southern Power | Production Tax Credit Carryforward |  |  |
Income Tax Disclosure [Line Items] |  |  |
Effective income tax rate reconciliation, tax credit, production, amount | 32 | 26 | 27
Georgia Power |  |  |
Income Tax Disclosure [Line Items] |  |  |
Deferred income tax assets | 3,564 | 3,718 |
State investment tax credit carryforward | 472 |  |
Georgia Power | Production Tax Credit Carryforward |  |  |
Income Tax Disclosure [Line Items] |  |  |
Payments for transferred tax credit | 131 | 39 |
Mississippi Power |  |  |
Income Tax Disclosure [Line Items] |  |  |
Deferred income tax assets | 358 | 382 |
Southern Company Gas |  |  |
Income Tax Disclosure [Line Items] |  |  |
Deferred income tax assets | 493 | 377 |
State and Local Jurisdiction |  |  |
Income Tax Disclosure [Line Items] |  |  |
Valuation allowance | 161 |  |
Change in valuation allowance | 101 |  |
State and Local Jurisdiction | Georgia Power |  |  |
Income Tax Disclosure [Line Items] |  |  |
Valuation allowance | 124 |  |
Change in valuation allowance | 64 |  |
Proceeds From Tax Credit Transfer | 11 |  |
State and Local Jurisdiction | Georgia Power | ITCs and other credits carryforward |  |  |
Income Tax Disclosure [Line Items] |  |  |
Reduction in income tax expense, investment tax credits | 44 | $ 49 | 53
Deferred Charges Related To Income Taxes, Current | Other Noncurrent Assets | Southern Power | Unrealized Tax Credits |  |  |
Income Tax Disclosure [Line Items] |  |  |
Deferred income tax assets | 0 |  | $ 17
Mississippi | Mississippi Power |  |  |
Income Tax Disclosure [Line Items] |  |  |
Operating loss carryforwards, valuation allowance | 32 |  |
Oklahoma | Southern Power |  |  |
Income Tax Disclosure [Line Items] |  |  |
Operating loss carryforwards, valuation allowance | 11 |  |
Florida | Southern Power |  |  |
Income Tax Disclosure [Line Items] |  |  |
Operating loss carryforwards, valuation allowance | $ 10 |  |

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