Introduction - Schedule of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 713	$ 748
Restricted cash:
Total cash, cash equivalents, and restricted cash	832	921	$ 1,217	$ 2,037
Other current assets
Restricted cash:
Restricted cash	99	141
Other deferred charges and assets
Restricted cash:
Restricted cash	19	31
ALABAMA POWER CO
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	292	324
Restricted cash:
Total cash, cash equivalents, and restricted cash	336	409	427	687
ALABAMA POWER CO | Other current assets
Restricted cash:
Restricted cash	44	85
ALABAMA POWER CO | Other deferred charges and assets
Restricted cash:
Restricted cash	0	0
GEORGIA POWER CO
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	0	9
Restricted cash:
Total cash, cash equivalents, and restricted cash	55	75	160	480
GEORGIA POWER CO | Other current assets
Restricted cash:
Restricted cash	36	37
GEORGIA POWER CO | Other deferred charges and assets
Restricted cash:
Restricted cash	19	29
SOUTHERN POWER CO
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	115	124
Restricted cash:
Total cash, cash equivalents, and restricted cash	132	144	126	133
SOUTHERN POWER CO | Other current assets
Restricted cash:
Restricted cash	17	17
SOUTHERN POWER CO | Other deferred charges and assets
Restricted cash:
Restricted cash	0	3
SOUTHERN POWER CO | Proceeds From Issuance Of Solid Waste Disposal Facility Revenue Bonds
Restricted cash:
Restricted cash	17	17
SOUTHERN POWER CO | Estimated Construction Completion Costs | Deuel Harvest
Restricted cash:
Restricted cash		3
SOUTHERN Co GAS
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	77	33
Restricted cash:
Total cash, cash equivalents, and restricted cash	79	35	$ 89	$ 83
SOUTHERN Co GAS | Other current assets
Restricted cash:
Restricted cash	2	2
SOUTHERN Co GAS | Other deferred charges and assets
Restricted cash:
Restricted cash	$ 0	$ 0