Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (4,547)	$ (2,468)
Other comprehensive income (loss):
Unrealized gain on marketable securities	4
Total comprehensive loss	$ (4,543)	$ (2,468)