Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Deferred tax assets, valuation allowance	$ 87		$ 87
Effective tax rate (as a percent)		(44.30%)		(37.50%)
Loss from continuing operations before income taxes	$ (36)	$ (75)	$ (62)	$ (152)