Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Product revenue	$ 599
Research revenue	2,214	$ 119	$ 266
Total revenue	2,813	119	266
Costs and expenses:
Cost of product revenue	1,740
Research and development	25,362	19,782	14,936
Selling, general and administrative	19,094	11,018	5,022
Total costs and expenses	46,196	30,800	19,958
Loss from operations	(43,383)	(30,681)	(19,692)
Interest expense, net	(1,967)	(721)	(403)
Other income (expense), net	60	12	(515)
Net loss and comprehensive loss	(45,290)	(31,390)	(20,610)
Accretion of redeemable convertible preferred stock to redemption value		(4,570)	(6,908)
Net loss applicable to common stockholders	$ (45,290)	$ (35,960)	$ (27,518)
Net loss per share applicable to common stockholders - basic and diluted	$ (2.21)	$ (4.15)	$ (19.72)
Weighted-average number of common shares used in computing net loss per share applicable to common stockholders - basic and diluted	20,501,748	8,674,931	1,395,562