Income Taxes (Schedule of Income Tax (Expense) Benefit) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current income tax benefit (expense)
Federal	$ (1)	$ 48	$ 279
State	(20)	15	13
Total current income tax benefit	21	(63)	(292)
Deferred income tax (expense) benefit
Federal	(136)	(270)	963
State	(95)	40	(196)
Total deferred income tax (expense) benefit	(231)	(230)	767
Foreign income tax benefit (expense)	(2)	1	(1)
Total income tax (expense) benefit	$ (254)	$ (166)	$ 1,058