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CONSOLIDATED ENTITIES AND EQUITY METHOD INVESTMENTS - GAS Equity Method Investments Narrative (Details) $ in Millions | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2021 USD ($) | Jun. 30, 2021 USD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2014 mi
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Impairment charges |  |  | $ 0 | $ 251 | $ 2 |
Income taxes (benefit) |  |  | 496 | 795 | 267 |
Southern Company Gas |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Impairment charges |  |  | 0 | 131 | 0 |
Income taxes (benefit) |  |  | 211 | $ 180 | 275 |
Southern Company Gas | PennEast Pipeline |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Ownership percentage, equity method investment |  |  |  |  |  | 20.00%
Pipeline infrastructure (miles) | mi |  |  |  |  |  | 118
Impairment charges | $ 2 | $ 82 | 84 |  | 84 |
Impairment charges, after tax | $ 2 | $ 58 | $ 67 |  | 67 |
Income taxes (benefit) |  |  |  |  | $ 7 |

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