Consolidated Statements of Total Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement Of Comprehensive Income [Abstract]
Shareholders' comprehensive income (loss)	$ 388	$ 608	$ 1,736	$ 827
Net income attributable to redeemable noncontrolling interest	(2)	0	3	3
Net income attributable to other noncontrolling interest	(1)	0	(6)	0
Other comprehensive income (loss) attributable to redeemable noncontrolling interest	(6)	(6)	(6)	(15)
Other comprehensive income (loss) attributable to other noncontrolling interest	0	0	1	0
Total comprehensive income	$ 379	$ 602	$ 1,728	$ 815