Introduction - Schedule of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 1,018	$ 748
Restricted cash:
Total cash, cash equivalents, and restricted cash	1,055	921	$ 1,890	$ 2,037
Other current assets
Restricted cash:
Restricted cash	31	141
Other deferred charges and assets
Restricted cash:
Restricted cash	7	31
ALABAMA POWER CO
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	476	324
Restricted cash:
Total cash, cash equivalents, and restricted cash	476	409	729	687
ALABAMA POWER CO | Other current assets
Restricted cash:
Restricted cash	0	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	43	9
Restricted cash:
Total cash, cash equivalents, and restricted cash	64	75	256	480
GEORGIA POWER CO | Other current assets
Restricted cash:
Restricted cash	14	37
GEORGIA POWER CO | Other deferred charges and assets
Restricted cash:
Restricted cash	7	29
SOUTHERN POWER CO
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	179	124
Restricted cash:
Total cash, cash equivalents, and restricted cash	195	144	257	133
SOUTHERN POWER CO | Other current assets
Restricted cash:
Restricted cash	16	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	16	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	44	33
Restricted cash:
Total cash, cash equivalents, and restricted cash	45	35	$ 399	$ 83
SOUTHERN Co GAS | Other current assets
Restricted cash:
Restricted cash	1	2
SOUTHERN Co GAS | Other deferred charges and assets
Restricted cash:
Restricted cash	$ 0	$ 0