Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Income Taxes (Textual) [Abstract]
Total income tax expense (benefit), rate	27.00%	25.00%	28.20%
Combined federal and state statutory tax rate	37.20%
Federal net deferred tax asset	$ 81	$ 111
State deferred tax liability	23	19
Combined net federal and state deferred tax assets			$ 348