DERIVATIVES - Derivative Financial Statement Presentation and Amounts With Balance Sheet Offsetting (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Fair value of energy-related derivatives and interest rate derivatives
Derivative asset, gross amounts recognized	$ 89	$ 55
Derivative asset, gross amount offset	(44)	(23)
Derivative asset, net amounts recognized in the balance sheets	45	32
Derivative liability, gross amounts recognized	615	744
Derivative liability, gross amounts offset	$ (61)	$ (85)
Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	Net amounts recognized in the Balance Sheets(b)	Net amounts recognized in the Balance Sheets(b)
Derivative liability, gross amounts recognized in balance sheets	$ 554	$ 659
Derivative asset, statement of financial position, extensible enumeration, not disclosed, flag	Net amounts recognized in the Balance Sheets(b)	Net amounts recognized in the Balance Sheets(b)
Collateral already posted, aggregate fair value	$ 17	$ 62
Not Designated as Hedging Instrument
Fair value of energy-related derivatives and interest rate derivatives
Derivative asset, gross amounts recognized	6	9
Derivative liability, gross amounts recognized	3	10
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	1
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	2
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	5	8
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	3	8
Interest rate derivatives
Fair value of energy-related derivatives and interest rate derivatives
Derivative liability, gross amounts recognized in balance sheets	72
Alabama Power
Fair value of energy-related derivatives and interest rate derivatives
Derivative asset, gross amount offset	(19)	(10)
Derivative asset, net amounts recognized in the balance sheets	7	5
Derivative liability, gross amounts offset	(19)	(10)
Derivative liability, gross amounts recognized in balance sheets	23	100
Collateral already posted, aggregate fair value	0
Georgia Power
Fair value of energy-related derivatives and interest rate derivatives
Derivative asset, gross amounts recognized	19	13
Derivative asset, gross amount offset	(15)	(11)
Derivative asset, net amounts recognized in the balance sheets	4	2
Derivative liability, gross amounts recognized	42	124
Derivative liability, gross amounts offset	(15)	(11)
Derivative liability, gross amounts recognized in balance sheets	27	113
Georgia Power \| Not Designated as Hedging Instrument
Fair value of energy-related derivatives and interest rate derivatives
Derivative asset, gross amounts recognized	0	1
Derivative liability, gross amounts recognized	1	0
Georgia Power \| 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	0	1
Georgia Power \| 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	0
Georgia 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	1	0
Georgia 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	0	0
Mississippi Power
Fair value of energy-related derivatives and interest rate derivatives
Derivative asset, gross amount offset	(17)	(14)
Derivative asset, net amounts recognized in the balance sheets	2	1
Derivative liability, gross amounts offset	(17)	(14)
Derivative liability, gross amounts recognized in balance sheets	17	47
Southern Power
Fair value of energy-related derivatives and interest rate derivatives
Derivative asset, net amounts recognized in the balance sheets	4	3
Derivative liability, gross amounts recognized in balance sheets	51	27
Collateral already posted, aggregate fair value	0
Southern Power \| Interest rate derivatives
Fair value of energy-related derivatives and interest rate derivatives
Derivative liability, gross amounts recognized in balance sheets	24
Southern Company Gas
Fair value of energy-related derivatives and interest rate derivatives
Derivative asset, gross amounts recognized	21	9
Derivative asset, gross amount offset	7	12
Derivative asset, net amounts recognized in the balance sheets	28	21
Derivative liability, gross amounts recognized	94	137
Derivative liability, gross amounts offset	(10)	(50)
Derivative liability, gross amounts recognized in balance sheets	84	87
Collateral already posted, aggregate fair value	17	62
Southern Company Gas \| Not Designated as Hedging Instrument
Fair value of energy-related derivatives and interest rate derivatives
Derivative asset, gross amounts recognized	6	8
Derivative liability, gross amounts recognized	2	10
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	1
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	2
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	5	7
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	2	8
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	75	43
Derivative liability, gross amounts recognized	122	315
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	42	31
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	40	117
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	33	12
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	82	198
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	26	15
Derivative liability, gross amounts recognized	42	110
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	15	9
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	12	41
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	30	69
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	11	6
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	19	12
Derivative liability, gross amounts recognized	41	124
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	13	10
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	9	42
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	32	82
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	6	2
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	19	15
Derivative liability, gross amounts recognized	34	61
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	14	12
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	19	34
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	15	27
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	5	3
Hedging Instruments for Regulatory Purposes \| Southern Company Gas \| 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
Hedging Instruments for Regulatory Purposes \| Southern Company Gas \| 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	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	11	1
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	5	20
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	8	3
Derivative liability, gross amounts recognized	490	419
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	4	3
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	4
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	4	0
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	3	29
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	208	190
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	0	0
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	61	74
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	0
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	182	88
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	36	34
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	4	3
Derivative liability, gross amounts recognized	51	27
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	3	3
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	5
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	1	0
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	0
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	40	11
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	11	11
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	4	0
Derivative liability, gross amounts recognized	87	107
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	3	0
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	3	24
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	67	59
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	0	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	$ 17	$ 20

Derivative Asset, Statement Of Financial Position, Extensible Enumeration, Not Disclosed, Flag

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- Definition

Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag

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- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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- Definition

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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