Income Taxes - Components of Loss Before Income Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Domestic	$ (56,237)	$ (38,702)	$ (17,014)
Foreign	(13,447)	(606)
Loss before income tax	$ (69,684)	$ (39,308)	$ (17,014)