Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Income Taxes (Textuals) [Abstract]
Tax expenses	$ 53	$ 94	$ 164	$ 220
Income before income taxes	186	305	408	611
Income Tax Reconciliation, Change in Enacted Tax Rate	4
Income Tax Reconciliation, Tax Contingencies		5	10	23
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