Income Taxes (Schedule of Income Tax (Expense) Benefit) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current income tax benefit (expense)
Federal	$ 34	$ (1)	$ 48
State	22	(20)	15
Total current income tax benefit	(56)	21	(63)
Deferred income tax (expense) benefit
Federal	(199)	(136)	(270)
State	(10)	(95)	40
Total deferred income tax (expense) benefit	(209)	(231)	(230)
Foreign income tax benefit (expense)	(1)	(2)	1
Total income tax (expense) benefit	$ (154)	$ (254)	$ (166)