Segment and Related Information - Schedule of Financial Data for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Concentration Risk [Line Items]
Operating revenues	$ 7,206	$ 5,198	$ 13,854	$ 11,108
Retail
Concentration Risk [Line Items]
Operating revenues	4,789	3,599	8,402	6,941
Wholesale Electric
Concentration Risk [Line Items]
Operating revenues	937	546	1,601	1,091
Natural Gas
Concentration Risk [Line Items]
Operating revenues	1,083	677	3,140	2,371
Electric Utilities
Concentration Risk [Line Items]
Operating revenues	6,006	4,407	10,516	8,524
Electric Utilities | Retail
Concentration Risk [Line Items]
Operating revenues	4,789	3,599	8,402	6,941
Electric Utilities | Wholesale Electric
Concentration Risk [Line Items]
Operating revenues	937	546	1,601	1,091
Electric Utilities | Other Revenue
Concentration Risk [Line Items]
Operating revenues	280	262	513	492
Southern Company Gas' Revenues
Concentration Risk [Line Items]
Operating revenues	1,083	677	3,140	2,371
Southern Company Gas' Revenues | Gas Distribution Operations
Concentration Risk [Line Items]
Operating revenues	975	706	2,765	1,898
Southern Company Gas' Revenues | Wholesale Gas Services
Concentration Risk [Line Items]
Operating revenues	0	(110)	0	188
Southern Company Gas' Revenues | Gas marketing services
Concentration Risk [Line Items]
Operating revenues	92	64	335	259
Southern Company Gas' Revenues | Other
Concentration Risk [Line Items]
Operating revenues	16	17	40	26
Southern Company Gas' Revenues
Concentration Risk [Line Items]
Operating revenues	$ 1,083	677	$ 3,140	2,371
Southern Company Gas' Revenues | Wholesale Gas Services
Concentration Risk [Line Items]
Operating revenues		(110)		188
Less Gross Gas Costs		1,429		3,783
Third Party Gross Revenues | Southern Company Gas' Revenues | Wholesale Gas Services
Concentration Risk [Line Items]
Operating revenues		1,292		3,881
Intercompany Revenues | Southern Company Gas' Revenues | Wholesale Gas Services
Concentration Risk [Line Items]
Operating revenues		27		90
Total Gross Revenues | Southern Company Gas' Revenues | Wholesale Gas Services
Concentration Risk [Line Items]
Operating revenues		$ 1,319		$ 3,971