Noncontrolling Interest - Net Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interest	$ (12)	$ 2
Net Income (Loss)	2,435	2,031	$ 1,710
Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interest	(12)	2
Southern Power [Member]
Noncontrolling Interest [Line Items]
Net income attributable to Southern Power Company	215	172	166
Net Income (Loss) Attributable to Noncontrolling Interest	12	(2)
Net income attributable to redeemable noncontrolling interest	2	4	4
Net Income (Loss)	229	175	$ 166
Southern Power [Member] | Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interest	$ 12	(2)
Southern Power [Member] | Noncontrolling Interests [Member]
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interest		$ (1)