Introduction - Schedule of Other Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Other intangible assets subject to amortization:
Gross Carrying Amount	$ 677	$ 677
Accumulated Amortization	(317)	(307)
Other Intangible Assets, Net	360	370
Other intangible assets not subject to amortization:
Federal Communications Commission licenses	75	75
Total other intangible assets
Gross Carrying Amount	752	752
Accumulated Amortization	(317)	(307)
Other Intangible Assets, Net	435	445
Customer relationships
Other intangible assets subject to amortization:
Gross Carrying Amount	212	212
Accumulated Amortization	(152)	(150)
Other Intangible Assets, Net	60	62
Total other intangible assets
Accumulated Amortization	(152)	(150)
Trade names
Other intangible assets subject to amortization:
Gross Carrying Amount	64	64
Accumulated Amortization	(41)	(38)
Other Intangible Assets, Net	23	26
Total other intangible assets
Accumulated Amortization	(41)	(38)
PPA fair value adjustments
Other intangible assets subject to amortization:
Gross Carrying Amount	390	390
Accumulated Amortization	(114)	(109)
Other Intangible Assets, Net	276	281
Total other intangible assets
Accumulated Amortization	(114)	(109)
Other
Other intangible assets subject to amortization:
Gross Carrying Amount	11	11
Accumulated Amortization	(10)	(10)
Other Intangible Assets, Net	1	1
Total other intangible assets
Accumulated Amortization	(10)	(10)
SOUTHERN POWER CO
Other intangible assets subject to amortization:
Accumulated Amortization	(114)	(109)
Total other intangible assets
Accumulated Amortization	(114)	(109)
SOUTHERN POWER CO | PPA fair value adjustments
Other intangible assets subject to amortization:
Gross Carrying Amount	390	390
Accumulated Amortization	(114)	(109)
Other Intangible Assets, Net	276	281
Total other intangible assets
Accumulated Amortization	(114)	(109)
SOUTHERN Co GAS
Other intangible assets subject to amortization:
Gross Carrying Amount	182	182
Accumulated Amortization	(148)	(145)
Other Intangible Assets, Net	34	37
Total other intangible assets
Accumulated Amortization	(148)	(145)
Other Intangible Assets, Net	34	37
SOUTHERN Co GAS | Customer relationships
Other intangible assets subject to amortization:
Gross Carrying Amount	156	156
Accumulated Amortization	(132)	(130)
Other Intangible Assets, Net	24	26
Total other intangible assets
Accumulated Amortization	(132)	(130)
SOUTHERN Co GAS | Trade names
Other intangible assets subject to amortization:
Gross Carrying Amount	26	26
Accumulated Amortization	(16)	(15)
Other Intangible Assets, Net	10	11
Total other intangible assets
Accumulated Amortization	$ (16)	$ (15)