Income Taxes (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at beginning of year	$ 110	$ 123	$ 213
Additions based on tax positions related to the current year	13	(1)	23
Additions for tax positions of prior years			77
Reductions for tax positions of prior years	(4)	(12)	(92)
Settlements	(22)		(98)
Balance at end of year	$ 97	$ 110	$ 123