Income Taxes (Narrative - Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits that would impact effective tax rate	$ 34	$ 12	$ 9
Unrecognized tax benefits, interest and penalties accrued	1	1	1
Unrecognized tax benefits, interest and penalties	1	$ 1	$ 1
Change in unrecognized tax benefits that is reasonably possible, amount	$ 41