Income Taxes (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accrued interest for unrecognized tax benefits
Interest accrued at beginning of year	$ 29	$ 21	$ 15
Interest reclassified due to settlements	(24)
Interest accrued during the period	5	8	6
Balance at end of year	$ 10	$ 29	$ 21

This element represents the amount of interest expense accrued as of the date of the statement of financial position for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity.

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This element represents interest expense recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity.

+ References+ Details