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CONTINGENCIES, COMMITMENTS, AND GUARANTEES - Guarantees (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 | Dec. 31, 2022
Recorded Unconditional Purchase Obligation [Line Items] |  |
Notes payable | $ 2,314 | $ 2,609
Alabama Power |  |
Recorded Unconditional Purchase Obligation [Line Items] |  |
Jointly owned affiliate equity | 69 |
Jointly owned affiliate long term debt | 100 |
Notes payable | 40 | $ 0
SEGCO | Alabama Power |  |
Recorded Unconditional Purchase Obligation [Line Items] |  |
Guarantee of unsecured senior notes | 100 |
Notes payable | $ 0 |

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