Noncontrolling Interest - Textuals (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Southern Power [Member]
Redeemable Noncontrolling Interest [Line Items]
Net income attributable to redeemable noncontrolling interest	$ 2	$ 4	$ 4