Revenue from Contracts with Customers and Lease Income - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Contract liabilities	$ 235	$ 235	$ 116
Contract assets	304	304	271
Revenue from contracts with customers recognized	52	77
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	42	42	1
Contract assets	130	130	121
Revenue from contracts with customers recognized	0	0
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Contract liabilities	0	0	0
Contract assets	67	67	56
Revenue from contracts with customers recognized	0	0
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	2	2	0
Contract assets	0	0	2
Revenue from contracts with customers recognized	0	0
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	0	0	0
Contract assets	0	0	0
Revenue from contracts with customers recognized	0	0
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	1	1	4
Contract assets	0	0	0
Revenue from contracts with customers recognized	0	$ 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	68	$ 68
Unregulated Distributed Generation
Disaggregation of Revenue [Line Items]
Contract liabilities	190	190	115
Contract assets	$ 118	$ 118	$ 91