Introduction - Schedule of Other Intangible Assets (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Subject to amortization:
Gross Carrying Amount	$ 669	$ 671
Accumulated Amortization	(367)	(340)
Other Intangible Assets, Net	302	331
Not subject to amortization:
FCC licenses	75	75
Total other intangible assets
Gross Carrying Amount	744	746
Accumulated Amortization	(367)	(340)
Other Intangible Assets, Net	377	406
Customer relationships
Subject to amortization:
Gross Carrying Amount	211	212
Accumulated Amortization	(169)	(162)
Other Intangible Assets, Net	42	50
Total other intangible assets
Accumulated Amortization	(169)	(162)
Trade names
Subject to amortization:
Gross Carrying Amount	63	64
Accumulated Amortization	(50)	(44)
Other Intangible Assets, Net	13	20
Total other intangible assets
Accumulated Amortization	(50)	(44)
PPA fair value adjustments
Subject to amortization:
Gross Carrying Amount	390	390
Accumulated Amortization	(143)	(129)
Other Intangible Assets, Net	247	261
Total other intangible assets
Accumulated Amortization	(143)	(129)
Other
Subject to amortization:
Gross Carrying Amount	5	5
Accumulated Amortization	(5)	(5)
Other Intangible Assets, Net	0	0
Total other intangible assets
Accumulated Amortization	(5)	(5)
SOUTHERN POWER CO
Subject to amortization:
Accumulated Amortization	(143)	(129)
Total other intangible assets
Accumulated Amortization	(143)	(129)
SOUTHERN POWER CO | PPA fair value adjustments
Subject to amortization:
Gross Carrying Amount	390	390
Accumulated Amortization	(143)	(129)
Other Intangible Assets, Net	247	261
Total other intangible assets
Accumulated Amortization	(143)	(129)
SOUTHERN Co GAS
Subject to amortization:
Gross Carrying Amount	182	182
Accumulated Amortization	(163)	(156)
Other Intangible Assets, Net	19	26
Total other intangible assets
Accumulated Amortization	(163)	(156)
Other Intangible Assets, Net	19	26
SOUTHERN Co GAS | Customer relationships
Subject to amortization:
Gross Carrying Amount	156	156
Accumulated Amortization	(143)	(139)
Other Intangible Assets, Net	13	17
Total other intangible assets
Accumulated Amortization	(143)	(139)
SOUTHERN Co GAS | Trade names
Subject to amortization:
Gross Carrying Amount	26	26
Accumulated Amortization	(20)	(17)
Other Intangible Assets, Net	6	9
Total other intangible assets
Accumulated Amortization	$ (20)	$ (17)