Consolidated Statements of Total Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Comprehensive Income [Abstract]
Shareholders' comprehensive income (loss)	$ 1,780	$ 1,686	$ 1,627
Net income (loss) attributable to redeemable noncontrolling interest	(6)	1	2
Net income (loss) attributable to other noncontrolling interest	(11)	(9)	0
Other comprehensive income (loss) attributable to redeemable noncontrolling interest	(17)	(7)	(19)
Other comprehensive income (loss) attributable to other noncontrolling interest	(1)	1	0
Total comprehensive income	$ 1,745	$ 1,672	$ 1,610