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Income Taxes (Details) - USD ($) $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Dec. 31, 2024
Income Tax Contingency [Line Items] |  |  |
Effective tax (benefit) rate | 20.30% | 19.00% |
Unrecognized tax benefits | $ 380 |  | $ 82
ALABAMA POWER CO |  |  |
Income Tax Contingency [Line Items] |  |  |
Sale of investment tax credit | $ 80 |  |
Effective tax (benefit) rate | 23.00% | 21.20% |
Unrecognized tax benefits | $ 144 |  | 0
GEORGIA POWER CO |  |  |
Income Tax Contingency [Line Items] |  |  |
Sale of investment tax credit | 64 |  |
Payment for PTCs | $ 121 |  |
Effective tax (benefit) rate | 20.00% | 18.70% |
Unrecognized tax benefits | $ 188 |  | $ 34
SOUTHERN POWER CO |  |  |
Income Tax Contingency [Line Items] |  |  |
Sale of investment tax credit | $ 19 |  |
Effective tax (benefit) rate | 6.00% | 14.40% |
MISSISSIPPI POWER CO |  |  |
Income Tax Contingency [Line Items] |  |  |
Effective tax (benefit) rate | 22.50% | 20.00% |
SOUTHERN Co GAS |  |  |
Income Tax Contingency [Line Items] |  |  |
Effective tax (benefit) rate | 23.50% | 24.90% |

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- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 12 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482685/740-10-50-12 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 231 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482663/740-10-55-231 + Details
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