Revenue from Contracts with Customers and Lease Income - Schedule of Contract Balances (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Accounts Receivable	$ 2,433	$ 3,123
Contract Assets	160	156
Contract Liabilities	61	45
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	622	696
Contract Assets	3	2
Contract Liabilities	2	4
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	672	922
Contract Assets	74	89
Contract Liabilities	14	9
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	79	92
Contract Assets	0	0
Contract Liabilities	1	0
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	119	237
Contract Assets	0	0
Contract Liabilities	1	1
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Accounts Receivable	853	1,107
Contract Assets	19	0
Contract Liabilities	$ 0	$ 0