Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (47,973)	$ (24,350)	$ (20,014)
Other comprehensive loss:
Change in unrealized loss on available for sale investments	(171)
Comprehensive loss	$ (48,144)	$ (24,350)	$ (20,014)