Income Taxes (Unrecognized tax benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns, Net [Roll Forward]
Balance at January 1	$ 7	$ 7
Additions for tax positions of prior years	1	0
Reductions for tax positions of prior years	(1)	0
Settlements	(4)	0
Balance at December 31	$ 3	$ 7