Income Taxes (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Unrecognized Tax Benefits Rollforward (Table Amounts) [Abstract]
Unrecognized tax benefits at beginning of the year	$ 118	$ 126	$ 429
Additions based on tax positions related to the current year	12	11	19
Additions for tax positions of prior years	28	31	4
Reductions for tax positions of prior years	(1)	(22)	0
Settlements	(1)	(28)	(326)
Net change in unrecognized tax benefits	38	(8)	(303)
Unrecognized tax benefits at end of the year	$ 156	$ 118	$ 126