Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Income Taxes (Textuals) [Abstract]
Tax expenses	$ 63	$ 64	$ 111	$ 126
Income before income taxes	166	120	222	306
Income Tax Reconciliation, Tax Contingencies			6	18
Unrecognized tax benefits, if recognized, would have a favorable impact on our tax expense					90
Tax expense, that would have a favorable impact of Unrecognized tax benefits					84
Accrued Interest					24
Unsettled unrecognized tax benefits that would require cash					$ 23