Income Taxes (Unrecognized tax benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns, Net [Roll Forward]
Balance at January 1	$ 3	$ 7
Additions for tax positions of prior years	1	1
Reductions for tax positions of prior years	0	(1)
Settlements	0	(4)
Balance at December 31	$ 4	$ 3