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Derivatives - Schedule of Pre-Tax Effects of Cash Flow and Fair Value Hedging on Income (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Derivative [Line Items] |  |  |  |
Total other operations and maintenance | $ 1,662 | $ 1,424 | $ 4,543 | $ 4,352
Depreciation and amortization | 1,210 | 1,143 | 3,537 | 3,365
Total interest expense, net of amounts capitalized | (692) | (620) | (2,050) | (1,812)
Total other income (expense), net | 147 | 141 | 450 | 428
Natural gas |  |  |  |
Derivative [Line Items] |  |  |  |
Total cost of sales | 98 | 102 | 852 | 1,199
Other Income (Expense) |  |  |  |
Derivative [Line Items] |  |  |  |
Amount excluded from effectiveness testing recognized in earnings | 3 | (27) | 8 | (28)
Cash Flow Hedging | Energy-related derivatives | Cost of Sales |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | (4) | (4) | (34) | (32)
Cash Flow Hedging | Energy-related derivatives | Operating Expense |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | 0 | (1) | (1) | (2)
Cash Flow Hedging | Energy-related derivatives | Depreciation and Amortization |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | (3) | (5) | (5) | (18)
Cash Flow Hedging | Interest rate derivatives | Interest Expense |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | (4) | (22) | (12) | (31)
Cash Flow Hedging | Foreign currency derivatives | Interest Expense |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | (3) | (3) | (9) | (8)
Cash Flow Hedging | Foreign currency derivatives | Other Income (Expense) |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | 24 | (14) | 7 | (4)
Fair Value Hedging | Interest rate derivatives | Interest Expense |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | 78 | (47) | 47 | (50)
Fair Value Hedging | Foreign currency derivatives | Other Income (Expense) |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | 58 | (7) | 79 | 19
SOUTHERN POWER CO |  |  |  |
Derivative [Line Items] |  |  |  |
Total other operations and maintenance | 126 | 104 | 367 | 327
Depreciation and amortization | 133 | 130 | 378 | 380
Total interest expense, net of amounts capitalized | (30) | (32) | (89) | (98)
Total other income (expense), net | 2 | 4 | 8 | 8
SOUTHERN POWER CO | Cash Flow Hedging | Energy-related derivatives | Depreciation and Amortization |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | (3) | (5) | (5) | (18)
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives | Interest Expense |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | (3) | (3) | (9) | (8)
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives | Other Income (Expense) |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | 24 | (14) | 7 | (4)
SOUTHERN Co GAS |  |  |  |
Derivative [Line Items] |  |  |  |
Total cost of sales | 98 | 102 | 852 | 1,199
Total other operations and maintenance | 295 | 264 | 877 | 879
Depreciation and amortization | 162 | 145 | 475 | 429
Total interest expense, net of amounts capitalized | (84) | (77) | (250) | (226)
Total other income (expense), net | 16 | 19 | 49 | 50
SOUTHERN Co GAS | Natural gas |  |  |  |
Derivative [Line Items] |  |  |  |
Total cost of sales | 98 | 102 | 852 | 1,199
SOUTHERN Co GAS | Cash Flow Hedging | Energy-related derivatives | Cost of Sales |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | (4) | (4) | (34) | (32)
SOUTHERN Co GAS | Cash Flow Hedging | Energy-related derivatives | Operating Expense |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | 0 | (1) | (1) | (2)
SOUTHERN Co GAS | Cash Flow Hedging | Interest rate derivatives | Interest Expense |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | 0 | (18) | 0 | (18)
SOUTHERN Co GAS | Fair Value Hedging | Interest rate derivatives | Interest Expense |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (loss) on hedges | $ 28 | $ (11) | $ 18 | $ (14)

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