Revenue from Contracts with Customers and Lease Income - Schedule of Contract Balances (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Disaggregation of Revenue [Line Items]
Accounts Receivable	$ 3,106	$ 3,048
Contract Assets	304	323
Contract Liabilities	170	140
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	778	783
Contract Assets	0	3
Contract Liabilities	14	11
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	1,485	1,244
Contract Assets	134	184
Contract Liabilities	73	34
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	133	113
Contract Assets	0	0
Contract Liabilities	2	0
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	132	106
Contract Assets	0	0
Contract Liabilities	1	2
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Accounts Receivable	451	660
Contract Assets	74	72
Contract Liabilities	$ 0	$ 3