Revenue from Contracts with Customers and Lease Income - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Contract liabilities	$ 207	$ 116
Contract assets	290	271
Revenue from contracts with customers recognized	28
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	19	1
Contract assets	119	121
Revenue from contracts with customers recognized	0
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Contract liabilities	0	0
Contract assets	59	56
Revenue from contracts with customers recognized	0
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	0	0
Contract assets	3	2
Revenue from contracts with customers recognized	0
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	0	0
Contract assets	0	0
Revenue from contracts with customers recognized	0
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	1	4
Contract assets	0	0
Revenue from contracts with customers recognized	$ 0
Retail Customer Fixed Bill Programs | GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Contract term	1 year
Energy Efficiency Enhancement And Upgrade | SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Contract liabilities	$ 65
Unregulated Distributed Generation
Disaggregation of Revenue [Line Items]
Contract liabilities	188	115
Contract assets	$ 108	$ 91