Introduction - Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Indefinite-lived Intangible Assets [Line Items]
Goodwill	$ 264	$ 2
Total goodwill and other intangible assets - gross	768
Total goodwill and other intangible assets - net	754
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - gross carrying amount	429
Intangibles subject to amortization - accumulated amortization	(14)	(12)
Intangibles subject to amortization - net	415
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - accumulated amortization	$ 0
Customer Relationships [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - estimated useful life	14 years
Customer Relationships [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - estimated useful life	26 years
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - accumulated amortization	$ 0
Trade Names [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - estimated useful life	5 years
Trade Names [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - estimated useful life	9 years
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - accumulated amortization	$ 0
Patents [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - estimated useful life	3 years
Patents [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - estimated useful life	10 years
Order or Production Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - accumulated amortization	$ 0
Southern Company [Member]
Indefinite-lived Intangible Assets [Line Items]
Goodwill	262
Southern Company [Member] | Federal Communications Commission Licenses [Member]
Indefinite-lived Intangible Assets [Line Items]
Intangibles not subject to amortization	75
Southern Company [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - gross carrying amount	47
Intangibles subject to amortization - net	47
Southern Company [Member] | Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - gross carrying amount	43
Intangibles subject to amortization - net	43
Southern Company [Member] | Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - gross carrying amount	4
Intangibles subject to amortization - net	$ 4
Southern Company [Member] | Order or Production Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - estimated useful life	5 years
Intangibles subject to amortization - gross carrying amount	$ 5
Intangibles subject to amortization - net	5
Southern Power [Member]
Indefinite-lived Intangible Assets [Line Items]
Goodwill	2	2
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - accumulated amortization	$ (14)	$ (12)
Southern Power [Member] | PPA Fair Value Adjustments [Member]
Finite-Lived Intangible Assets [Line Items]
Intangibles subject to amortization - estimated useful life	20 years
Intangibles subject to amortization - gross carrying amount	$ 330
Intangibles subject to amortization - accumulated amortization	(14)
Intangibles subject to amortization - net	$ 316