Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (47,867)	$ (53,260)	$ (23,873)
Other comprehensive loss:
Unrealized loss on investments			(10)
Comprehensive loss	$ (47,867)	$ (53,260)	$ (23,883)