Consolidated Statements of Total Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement Of Comprehensive Income [Abstract]
Shareholders' comprehensive income (loss)	$ 585	$ 457	$ 2,020	$ 1,389
Net income (loss) attributable to redeemable noncontrolling interests	(1)	(1)	(4)	(2)
Net income (loss) attributable to other noncontrolling interests	(3)	(2)	(12)	(7)
Other comprehensive income (loss) attributable to redeemable noncontrolling interests	(3)	(9)	(1)	(21)
Other comprehensive income (loss) attributable to other noncontrolling interests	0	(1)	0	(1)
Total comprehensive (loss) attributable to noncontrolling interests	(7)	(13)	(17)	(31)
Total comprehensive income	$ 578	$ 444	$ 2,003	$ 1,358