Revenue from Contracts with Customers and Lease Income - Schedule of Contract Balances (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Accounts Receivable	$ 2,760	$ 2,504
Contract Assets	178	117
Contract Liabilities	56	57
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	800	589
Contract Assets	5	2
Contract Liabilities	5	4
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	1,035	736
Contract Assets	114	63
Contract Liabilities	6	14
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	98	73
Contract Assets	0	0
Contract Liabilities	7	0
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	264	149
Contract Assets	0	1
Contract Liabilities	2	1
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Accounts Receivable	433	753
Contract Assets	0	0
Contract Liabilities	$ 0	$ 0