Consolidated Statements of Total Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Comprehensive Income
Shareholders' comprehensive income (loss)	$ 510	$ 919	$ 1,199	$ 1,647
Comprehensive income (loss) attributable to noncontrolling interests:
Net income (loss) attributable to redeemable noncontrolling interests	2	(1)	4	(3)
Net income (loss) attributable to other noncontrolling interests	0	(2)	0	(5)
Other comprehensive income (loss) attributable to redeemable noncontrolling interests	(8)	2	(10)	0
Total comprehensive income (loss) attributable to noncontrolling interests	(6)	(1)	(6)	(8)
Total comprehensive income	$ 504	$ 918	$ 1,193	$ 1,639