CONSOLIDATED ENTITIES AND EQUITY METHOD INVESTMENTS - GAS Equity Method Investments Narrative (Details) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2014 mi
Schedule of Equity Method Investments [Line Items]
Impairment charges			$ 0	$ 251	$ 2
Income taxes (benefit)			496	795	267
Southern Company Gas
Schedule of Equity Method Investments [Line Items]
Impairment charges			0	131	0
Income taxes (benefit)			211	$ 180	275
Southern Company Gas | PennEast Pipeline
Schedule of Equity Method Investments [Line Items]
Ownership percentage, equity method investment						20.00%
Pipeline infrastructure (miles) | mi						118
Impairment charges	$ 2	$ 82	84		84
Impairment charges, after tax	$ 2	$ 58	$ 67		67
Income taxes (benefit)					$ 7