Consolidated Statements of Total Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement Of Comprehensive Income [Abstract]
Shareholders' comprehensive income (loss)	$ 733	$ 247	$ 1,348	$ 219
Net income attributable to redeemable noncontrolling interest	2	1	5	3
Net income attributable to other noncontrolling interest	(3)	0	(5)	0
Other comprehensive income (loss) attributable to redeemable noncontrolling interest	3	(6)	0	(9)
Other comprehensive income (loss) attributable to other noncontrolling interest	0	0	1	0
Total comprehensive income	$ 735	$ 242	$ 1,349	$ 213