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DERIVATIVES - Schedule of Unrealized Gain (Loss) Recognized in the Balance Sheet (Details) - Energy-related derivatives - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | $ (257) | $ 9
Other regulatory assets, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (180) | (71)
Other regulatory assets, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (87) | (23)
Other regulatory liabilities, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 9 | 72
Other regulatory liabilities, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 1 | 31
Alabama Power |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (95) | 23
Alabama Power | Other regulatory assets, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (67) | (8)
Alabama Power | Other regulatory assets, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (32) | (7)
Alabama Power | Other regulatory liabilities, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 4 | 29
Alabama Power | Other regulatory liabilities, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 0 | 9
Georgia Power |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (112) | (19)
Georgia Power | Other regulatory assets, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (80) | (26)
Georgia Power | Other regulatory assets, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (33) | (14)
Georgia Power | Other regulatory liabilities, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 0 | 19
Georgia Power | Other regulatory liabilities, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 1 | 2
Mississippi Power |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (46) | 27
Mississippi Power | Other regulatory assets, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (25) | (13)
Mississippi Power | Other regulatory assets, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (22) | (2)
Mississippi Power | Other regulatory liabilities, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 1 | 22
Mississippi Power | Other regulatory liabilities, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 0 | 20
Southern Company Gas |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (4) | (22)
Southern Company Gas | Other regulatory assets, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (8) | (24)
Southern Company Gas | Other regulatory assets, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 0 | 0
Southern Company Gas | Other regulatory liabilities, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 4 | 2
Southern Company Gas | Other regulatory liabilities, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | $ 0 | $ 0

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