Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2011	Jun. 30, 2012	Dec. 31, 2011
Income Taxes (Textual) [Abstract]
Total income tax expense (benefit), rate	19.80%	27.00%	27.10%
Combined federal and state statutory tax rate				37.20%
Federal net deferred tax asset	$ 119			$ 119	$ 111
State deferred tax liability	22			22	19
Combined net federal and state deferred tax assets			$ 208