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DERIVATIVES - Pre-Tax Effects of Derivatives Designated as Hedges on Income (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Total other operations and maintenance | $ 6,093 | $ 6,573 | $ 5,902
Depreciation and amortization | 4,525 | 3,663 | 3,565
Interest expense, net of amounts capitalized | (2,446) | (2,022) | (1,837)
Other income (expense), net | 553 | 500 | 449
Natural gas |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Cost of sales | 1,644 | 3,004 | 1,619
Energy-related derivatives | Cost of Sales | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (44) | 37 | 17
Energy-related derivatives | Operating Expense | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on hedges | (2) | 0 | 0
Energy-related derivatives | Depreciation and Amortization | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (23) | (5) | 9
Interest rate derivatives | Interest Expense | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (35) | (25) | (27)
Interest rate derivatives | Interest Expense | Fair Value Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | 37 | (291) | (30)
Foreign currency derivatives | Interest Expense | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (11) | (19) | (24)
Foreign currency derivatives | Other Income (Expense) | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | 19 | (83) | (104)
Gain (loss) on foreign currency fair value hedges | 69 | (106) | (63)
Amount excluded from effectiveness testing recognized in earnings | (21) | 24 | 3
Southern Power |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Total other operations and maintenance | 473 | 482 | 423
Depreciation and amortization | 504 | 516 | 517
Interest expense, net of amounts capitalized | (129) | (138) | (147)
Other income (expense), net | 12 | 7 | 10
Southern Power | Energy-related derivatives | Depreciation and Amortization | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (23) | (5) | 9
Southern Power | Foreign currency derivatives | Interest Expense | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (11) | (19) | (24)
Southern Power | Foreign currency derivatives | Other Income (Expense) | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | 19 | (83) | (104)
Southern Company Gas |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Cost of sales | 1,644 | 3,004 | 1,619
Total other operations and maintenance | 1,194 | 1,176 | 1,072
Depreciation and amortization | 582 | 559 | 536
Interest expense, net of amounts capitalized | (310) | (263) | (238)
Other income (expense), net | 57 | 53 | (53)
Southern Company Gas | Energy-related derivatives | Operating Expense | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on hedges | (2) | 0 | 0
Southern Company Gas | Interest rate derivatives | Interest Expense | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on hedges | (19) | (4) | 0
Southern Company Gas | Interest rate derivatives | Interest Expense | Fair Value Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on hedges | 6 | (86) | 0
Southern Company Gas | Foreign currency derivatives | Other Income (Expense) | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | $ (44) | $ 37 | $ 17

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