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Derivatives - Schedule of Pre-Tax Effects of Hedging on AOCI (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | $ (2) | $ 5 | $ (7) | $ (45)
Cash Flow Hedging | Energy-related derivatives |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | (7) | (4) | (11) | (55)
Cash Flow Hedging | Interest rate derivatives |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | (8) | (3) | 16 | (12)
Cash Flow Hedging | Foreign currency derivatives |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | 15 | (15) | (4) | (6)
Fair Value Hedging | Foreign currency derivatives |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | (2) | 27 | (8) | 28
GEORGIA POWER CO | Cash Flow Hedging | Interest rate derivatives |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | 1 | 0 | 17 | (3)
MISSISSIPPI POWER CO | Cash Flow Hedging | Interest rate derivatives |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | 0 | 0 | 7 | 0
SOUTHERN POWER CO |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | 13 | (15) | (6) | (20)
SOUTHERN POWER CO | Cash Flow Hedging | Energy-related derivatives |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | (2) | 0 | (2) | (14)
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | 15 | (15) | (4) | (6)
SOUTHERN Co GAS |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | (10) | (8) | (14) | (41)
SOUTHERN Co GAS | Cash Flow Hedging | Energy-related derivatives |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | (4) | (4) | (9) | (41)
SOUTHERN Co GAS | Cash Flow Hedging | Interest rate derivatives |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (Loss) Recognized in OCI on Derivatives | $ (6) | $ (4) | $ (5) | $ 0

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