Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Collaborative revenue	$ 6,880	$ 4,633	$ 4,157
Licensing revenue	0	7,000	3,500
Product sales	315	1,627	1,853
Total revenues	7,195	13,260	9,510
Operating expenses:
Cost of product sales	84	481	774
Research and development	43,670	45,134	33,087
General and administrative	16,253	21,859	15,134
Total operating expenses	60,007	67,474	48,995
Loss from operations	(52,812)	(54,214)	(39,485)
Interest and other income	950	684	40
Net loss	(51,862)	(53,530)	(39,445)
Unrealized loss on investments	(25)	(24)	0
Comprehensive loss	$ (51,887)	$ (53,554)	$ (39,445)
Basic and diluted net loss per share (in dollars per share)	$ (1.75)	$ (2.47)	$ (2.06)
Weighted-average shares used to compute basic and diluted net loss per share (in shares)	29,626,941	21,638,468	19,155,918