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DERIVATIVES - Pre-Tax Effects of Derivatives Designated as Hedges on AOCI (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | $ (58) | $ (80) | $ (67)
Energy-related derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (81) | 3 | 34
Interest rate derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (12) | 46 | 5
Foreign currency derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | 14 | (105) | (103)
Foreign currency derivatives | Fair Value Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | 21 | (24) | (3)
Georgia Power | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (2) | 31 | 0
Southern Power |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (4) | (120) | (91)
Southern Power | Energy-related derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | (18) | (15) | 12
Southern Power | Foreign currency derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | 14 | (105) | (103)
Southern Company Gas | Energy-related derivatives | Cash Flow Hedging |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) From Derivatives Recognized in OCI | $ (63) | $ 18 | $ 22

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- Definition Amount, before tax and after reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482790/220-10-45-11 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 10A -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482790/220-10-45-10A + Details
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