Consolidated Entities and Equity Method Investments - Schedule of Earnings (Loss) from Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Schedule of Equity Method Investments [Line Items]
Earnings (Loss) from Equity Method Investments	$ 34	$ (40)	$ 80	$ 5
SOUTHERN Co GAS
Schedule of Equity Method Investments [Line Items]
Earnings (Loss) from Equity Method Investments	31	(52)	71	(11)
Impairment of PennEast Pipeline investment			0	82
SOUTHERN Co GAS | SNG
Schedule of Equity Method Investments [Line Items]
Earnings (Loss) from Equity Method Investments	31	28	70	66
SOUTHERN Co GAS | PennEast Pipeline
Schedule of Equity Method Investments [Line Items]
Earnings (Loss) from Equity Method Investments	0	(81)	0	(79)
Impairment of PennEast Pipeline investment		82		82
Asset impairment charges, net of tax		58		58
SOUTHERN Co GAS | Other
Schedule of Equity Method Investments [Line Items]
Earnings (Loss) from Equity Method Investments	$ 0	$ 1	$ 1	$ 2