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DERIVATIVES - Schedule of Unrealized Gain (Loss) Recognized in the Balance Sheet (Details) - Energy-related derivatives - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | $ (50) | $ (257)
Other regulatory assets, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (61) | (180)
Other regulatory assets, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (5) | (87)
Other regulatory liabilities, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 8 | 9
Other regulatory liabilities, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 8 | 1
Alabama Power |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (16) | (95)
Alabama Power | Other regulatory assets, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (23) | (67)
Alabama Power | Other regulatory assets, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 0 | (32)
Alabama Power | Other regulatory liabilities, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 4 | 4
Alabama Power | Other regulatory liabilities, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 3 | 0
Georgia Power |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (22) | (112)
Georgia Power | Other regulatory assets, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (26) | (80)
Georgia Power | Other regulatory assets, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 0 | (33)
Georgia Power | Other regulatory liabilities, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 0 | 0
Georgia Power | Other regulatory liabilities, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 4 | 1
Mississippi Power |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (15) | (46)
Mississippi Power | Other regulatory assets, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (11) | (25)
Mississippi Power | Other regulatory assets, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (5) | (22)
Mississippi Power | Other regulatory liabilities, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 0 | 1
Mississippi Power | Other regulatory liabilities, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 1 | 0
Southern Company Gas |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | 3 | (4)
Southern Company Gas | Other regulatory assets, current |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | (1) | (8)
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 | 4
Southern Company Gas | Other regulatory liabilities, deferred |  |
Derivatives, Fair Value [Line Items] |  |
Total energy-related derivative gains (losses) | $ 0 | $ 0

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