Consolidated Statements of Changes in Equity (USD $) In Millions, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss, Net [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2010	$ 13,408	$ 0	$ 5,427	$ 7,979	$ (174)	$ 176
Balance (shares) at Dec. 31, 2010		75
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	994			979		15
Other comprehensive income (loss)	(454)				(454)	0
Distributions	(19)					(19)
Other equity transactions	(3)	0	(4)	0	0	1
Balance at Sep. 30, 2011	13,926	0	5,423	8,958	(628)	173
Balance (shares) at Sep. 30, 2011		75
Balance at Dec. 31, 2011	14,265	0	5,423	9,310	(641)	173
Balance (shares) at Dec. 31, 2011	75	75
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,161			1,145		16
Other comprehensive income (loss)	76				76	0
Distributions	(18)					(18)
Balance at Sep. 30, 2012	$ 15,484	$ 0	$ 5,423	$ 10,455	$ (565)	$ 171
Balance (shares) at Sep. 30, 2012	75	75