Income Taxes - Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Net loss before income taxes, United States	$ (29,162)	$ (40,180)
Net loss before income taxes, Foreign	(190)	(651)
Net loss before noncontrolling interest	$ (29,352)	$ (40,831)