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	575			567		8
Other comprehensive income (loss)	(181)				(181)	0
Distributions	(13)					(13)
Other equity transactions	(2)	0	(4)	0	0	2
Balance at Jun. 30, 2011	13,787	0	5,423	8,546	(355)	173
Balance (shares) at Jun. 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	666			657		9
Other comprehensive income (loss)	2				2	0
Distributions	(13)					(13)
Balance at Jun. 30, 2012	$ 14,920	$ 0	$ 5,423	$ 9,967	$ (639)	$ 169
Balance (shares) at Jun. 30, 2012	75	75