Income Taxes (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Unrecognized Tax Benefits	$ 4	$ 59	$ 18	$ 96
Additions for tax positions of current years	0	1	6
Additions for tax positions of prior years	0	45	1
Reductions for tax positions of prior years	(3)	(5)	0
Settlements	$ (52)	$ 0	$ (85)