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DERIVATIVES - Pre-Tax Effects of Derivatives Designated as Hedges on Income (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Depreciation and amortization | $ 3,565 | $ 3,518 | $ 3,038
Interest expense, net of amounts capitalized | (1,837) | (1,821) | (1,736)
Other income (expense), net | 456 | 336 | 252
Energy-related derivatives | Cost of Sales | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | 17 | (8) | (2)
Energy-related derivatives | Depreciation and Amortization | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | 9 | (3) | (6)
Interest rate derivatives | Interest Expense | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (27) | (26) | (20)
Interest rate derivatives | Interest Expense | Fair Value Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (30) | 27 | 42
Foreign currency derivatives | Interest Expense | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (24) | (23) | (24)
Foreign currency derivatives | Other Income (Expense) | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (104) | 114 | (24)
Gain (loss) on foreign currency fair value hedges | (63) | 0 | 0
Amount excluded from effectiveness testing recognized in earnings | 3 | 0 | 0
Southern Power |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Depreciation and amortization | 517 | 494 | 479
Interest expense, net of amounts capitalized | (147) | (151) | (169)
Other income (expense), net | 10 | 19 | 47
Southern Power | Energy-related derivatives | Depreciation and Amortization | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | 9 | (3) | (6)
Southern Power | Foreign currency derivatives | Interest Expense | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (24) | (23) | (24)
Southern Power | Foreign currency derivatives | Other Income (Expense) | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | (104) | 114 | (24)
Southern Company Gas |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Depreciation and amortization | 536 | 500 | 487
Interest expense, net of amounts capitalized | (238) | (231) | (232)
Other income (expense), net | (53) | 41 | 20
Southern Company Gas | Foreign currency derivatives | Other Income (Expense) | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative | $ 17 | $ (8) | $ (2)

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- Definition The current period expense charged against earnings on long-lived, physical assets used in the normal conduct of business and not intended for resale to allocate or recognize the cost of assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset. Excludes amortization of nuclear fuel. + References No definition available. + Details
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