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DERIVATIVES - Pre-Tax Effects of Derivatives Designated as Hedges on AOCI (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | $ (8) | $ (58) | $ (80)
Energy-related derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (7) | (81) | 3
Interest rate derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | 23 | (12) | 46
Foreign currency derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (40) | 14 | (105)
Foreign currency derivatives | Fair Value Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | 16 | 21 | (24)
Georgia Power | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | 24 | (2) | 31
Mississippi Power | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | 7 | 0 | 0
Southern Power |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (41) | (4) | (120)
Southern Power | Energy-related derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (1) | (18) | (15)
Southern Power | Foreign currency derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (40) | 14 | (105)
Southern Company Gas |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (11) | (63) | 18
Southern Company Gas | Energy-related derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (6) | (63) | 18
Southern Company Gas | Interest rate derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | $ (5) | $ 0 | $ 0

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