Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues [Abstract]
Product revenue	$ 631	$ 437
Research revenue	310	659
Total revenue	941	1,096
Costs and expenses:
Cost of product revenue	1,627	1,026
Research and development	6,585	6,589
Selling, general and administrative	5,874	6,204
Total costs and expenses	14,086	13,819
Loss from operations	(13,145)	(12,723)
Interest expense, net	(1,637)	(735)
Other income, net	79	32
Net loss and comprehensive loss	$ (14,703)	$ (13,426)
Net loss per share — basic and diluted (USD per share)	$ (0.48)	$ (0.55)
Weighted-average number of common shares used in computing net loss per share — basic and diluted (in shares)	30,531,180	24,218,767