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DERIVATIVES - Derivative Financial Statement Presentation and Amounts With Balance Sheet Offsetting (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
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Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | $ 238 | $ 810
Derivative asset, gross amount offset | (25) | (529)
Derivative asset, net amounts recognized in the balance sheets | 213 | 281
Derivative liability, gross amounts recognized | 153 | 621
Derivative liability, gross amounts offset | (28) | (557)
Derivative liability, gross amounts recognized in balance sheets | 125 | 64
Collateral already posted, aggregate fair value |  | 28
Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 10 | 658
Derivative liability, gross amounts recognized | 4 | 563
Energy-related derivatives | Other deferred charges and assets | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 1 | 270
Energy-related derivatives | Other deferred credits and liabilities | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 0 | 232
Energy-related derivatives | Assets from risk management activities | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 9 | 388
Energy-related derivatives | Other current liabilities | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 4 | 331
Alabama Power |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amount offset | (5) | (7)
Derivative asset, net amounts recognized in the balance sheets | 50 | 5
Derivative liability, gross amounts offset | (5) | (7)
Derivative liability, gross amounts recognized in balance sheets | 6 | 0
Georgia Power |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amount offset | (8) | (12)
Derivative asset, net amounts recognized in the balance sheets | 67 | 3
Derivative liability, gross amounts offset | (8) | (12)
Derivative liability, gross amounts recognized in balance sheets | 0 | 1
Mississippi Power |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amount offset | (4) | (7)
Derivative asset, net amounts recognized in the balance sheets | 52 | 2
Derivative liability, gross amounts offset | (4) | (7)
Derivative liability, gross amounts recognized in balance sheets | 1 | 2
Southern Power |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, net amounts recognized in the balance sheets | 4 | 89
Derivative liability, gross amounts recognized in balance sheets | 16 | 26
Southern Power | Energy-related derivatives | Other current liabilities | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 0 | 1
Southern Power | Energy-related derivatives | Other current assets | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 1 | 0
Southern Company Gas |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 35 | 665
Derivative asset, gross amount offset | (8) | (503)
Derivative asset, net amounts recognized in the balance sheets | 27 | 162
Derivative liability, gross amounts recognized | 27 | 566
Derivative liability, gross amounts offset | (11) | (531)
Derivative liability, gross amounts recognized in balance sheets | 16 | 35
Collateral already posted, aggregate fair value | 3 | 28
Southern Company Gas | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 9 | 658
Derivative liability, gross amounts recognized | 4 | 562
Southern Company Gas | Energy-related derivatives | Other deferred charges and assets | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 1 | 270
Southern Company Gas | Energy-related derivatives | Other deferred credits and liabilities | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 0 | 232
Southern Company Gas | Energy-related derivatives | Assets from risk management activities | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 8 | 388
Southern Company Gas | Energy-related derivatives | Other current liabilities | Not Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 4 | 330
Hedging Instruments for Regulatory Purposes | Energy-related derivatives | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 201 | 42
Derivative liability, gross amounts recognized | 36 | 30
Hedging Instruments for Regulatory Purposes | Energy-related derivatives | Other deferred charges and assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 72 | 18
Hedging Instruments for Regulatory Purposes | Energy-related derivatives | Other deferred credits and liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 6 | 19
Hedging Instruments for Regulatory Purposes | Energy-related derivatives | Assets from risk management activities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 129 | 24
Hedging Instruments for Regulatory Purposes | Energy-related derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 30 | 11
Hedging Instruments for Regulatory Purposes | Alabama Power | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 55 | 12
Derivative liability, gross amounts recognized | 11 | 7
Hedging Instruments for Regulatory Purposes | Alabama Power | Energy-related derivatives | Other deferred charges and assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 25 | 5
Hedging Instruments for Regulatory Purposes | Alabama Power | Energy-related derivatives | Other deferred credits and liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 2 | 5
Hedging Instruments for Regulatory Purposes | Alabama Power | Energy-related derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 9 | 2
Hedging Instruments for Regulatory Purposes | Alabama Power | Energy-related derivatives | Other current assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 30 | 7
Hedging Instruments for Regulatory Purposes | Georgia Power | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 75 | 15
Derivative liability, gross amounts recognized | 8 | 13
Hedging Instruments for Regulatory Purposes | Georgia Power | Energy-related derivatives | Other deferred charges and assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 21 | 8
Hedging Instruments for Regulatory Purposes | Georgia Power | Energy-related derivatives | Other deferred credits and liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 2 | 8
Hedging Instruments for Regulatory Purposes | Georgia Power | Energy-related derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 6 | 5
Hedging Instruments for Regulatory Purposes | Georgia Power | Energy-related derivatives | Other current assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 54 | 7
Hedging Instruments for Regulatory Purposes | Mississippi Power | Energy-related derivatives | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 56 | 9
Derivative liability, gross amounts recognized | 5 | 9
Hedging Instruments for Regulatory Purposes | Mississippi Power | Energy-related derivatives | Other deferred charges and assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 26 | 5
Hedging Instruments for Regulatory Purposes | Mississippi Power | Energy-related derivatives | Other deferred credits and liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 2 | 6
Hedging Instruments for Regulatory Purposes | Mississippi Power | Energy-related derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 3 | 3
Hedging Instruments for Regulatory Purposes | Mississippi Power | Energy-related derivatives | Other current assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 30 | 4
Hedging Instruments for Regulatory Purposes | Southern Company Gas | Energy-related derivatives | Assets from risk management activities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 15 | 6
Hedging Instruments for Regulatory Purposes | Southern Company Gas | Energy-related derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 12 | 1
Cash Flow and Fair Value Hedging | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 27 | 110
Derivative liability, gross amounts recognized | 113 | 28
Cash Flow and Fair Value Hedging | Energy-related derivatives | Other deferred charges and assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 1 | 0
Cash Flow and Fair Value Hedging | Energy-related derivatives | Other deferred credits and liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 0 | 0
Cash Flow and Fair Value Hedging | Energy-related derivatives | Assets from risk management activities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 7 | 3
Cash Flow and Fair Value Hedging | Energy-related derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 5 | 5
Cash Flow and Fair Value Hedging | Interest rate derivatives | Other deferred charges and assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 0 | 0
Cash Flow and Fair Value Hedging | Interest rate derivatives | Other deferred credits and liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 29 | 0
Cash Flow and Fair Value Hedging | Interest rate derivatives | Assets from risk management activities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 19 | 20
Cash Flow and Fair Value Hedging | Interest rate derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 0 | 0
Cash Flow and Fair Value Hedging | Foreign currency derivatives | Other deferred charges and assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 0 | 87
Cash Flow and Fair Value Hedging | Foreign currency derivatives | Other deferred credits and liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 40 | 0
Cash Flow and Fair Value Hedging | Foreign currency derivatives | Assets from risk management activities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 0 | 0
Cash Flow and Fair Value Hedging | Foreign currency derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 39 | 23
Cash Flow and Fair Value Hedging | Southern Power | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 3 | 89
Derivative liability, gross amounts recognized | 16 | 25
Cash Flow and Fair Value Hedging | Southern Power | Energy-related derivatives | Other deferred charges and assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 1 | 0
Cash Flow and Fair Value Hedging | Southern Power | Energy-related derivatives | Other deferred credits and liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 0 | 0
Cash Flow and Fair Value Hedging | Southern Power | Energy-related derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 0 | 2
Cash Flow and Fair Value Hedging | Southern Power | Energy-related derivatives | Other current assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 2 | 2
Cash Flow and Fair Value Hedging | Southern Power | Foreign currency derivatives | Other deferred charges and assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 0 | 87
Cash Flow and Fair Value Hedging | Southern Power | Foreign currency derivatives | Other deferred credits and liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 0 | 0
Cash Flow and Fair Value Hedging | Southern Power | Foreign currency derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 16 | 23
Cash Flow and Fair Value Hedging | Southern Power | Foreign currency derivatives | Other current assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 0 | 0
Cash Flow and Fair Value Hedging | Southern Company Gas | Energy-related derivatives | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 11 | 1
Derivative liability, gross amounts recognized | 11 | 3
Cash Flow and Fair Value Hedging | Southern Company Gas | Energy-related derivatives | Assets from risk management activities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 5 | 1
Cash Flow and Fair Value Hedging | Southern Company Gas | Energy-related derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 5 | 3
Cash Flow and Fair Value Hedging | Southern Company Gas | Interest rate derivatives | Other deferred charges and assets | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 0 | 0
Cash Flow and Fair Value Hedging | Southern Company Gas | Interest rate derivatives | Other deferred credits and liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | 6 | 0
Cash Flow and Fair Value Hedging | Southern Company Gas | Interest rate derivatives | Assets from risk management activities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative asset, gross amounts recognized | 6 | 0
Cash Flow and Fair Value Hedging | Southern Company Gas | Interest rate derivatives | Other current liabilities | Designated as Hedging Instrument |  |
Fair value of energy-related derivatives and interest rate derivatives |  |
Derivative liability, gross amounts recognized | $ 0 | $ 0

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