Segment and Related Information - Schedule of Financial Data for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Concentration Risk [Line Items]
Operating revenues	$ 6,480	$ 6,648
Electric Utilities
Concentration Risk [Line Items]
Operating revenues	4,483	4,509
Southern Company Gas' Revenues
Concentration Risk [Line Items]
Operating revenues	1,875	2,058
Retail
Concentration Risk [Line Items]
Operating revenues	3,599	3,613
Retail | Electric Utilities
Concentration Risk [Line Items]
Operating revenues	3,599	3,613
Wholesale Electric
Concentration Risk [Line Items]
Operating revenues	599	664
Wholesale Electric | Electric Utilities
Concentration Risk [Line Items]
Operating revenues	599	664
Other Revenue | Electric Utilities
Concentration Risk [Line Items]
Operating revenues	285	232
Natural Gas
Concentration Risk [Line Items]
Operating revenues	1,875	2,058
Gas Distribution Operations | Southern Company Gas' Revenues
Concentration Risk [Line Items]
Operating revenues	1,610	1,791
Gas marketing services | Southern Company Gas' Revenues
Concentration Risk [Line Items]
Operating revenues	246	243
Other | Southern Company Gas' Revenues
Concentration Risk [Line Items]
Operating revenues	$ 19	$ 24