Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Product sales	$ 26,685	$ 15,321	$ 11,376
Research and development revenues	20,748	31,316	25,599
Revenue sharing arrangement	2,591	2,200	4,829
Total revenues	50,024	48,837	41,804
Costs and operating expenses:
Cost of product sales	14,327	9,753	6,586
Research and development	29,659	22,229	20,673
Selling, general and administrative	29,008	25,419	22,315
Total costs and operating expenses	72,994	57,401	49,574
Loss from operations	(22,970)	(8,564)	(7,770)
Interest income	147	60	19
Other expense	(92)	(94)	(168)
Loss before income taxes	(22,915)	(8,598)	(7,919)
Provision for (benefit from) income taxes	81	(40)	(338)
Net loss	$ (22,996)	$ (8,558)	$ (7,581)
Net loss per share of common stock, basic and diluted (usd per share)	$ (0.50)	$ (0.21)	$ (0.19)
Weighted average common shares used in computing net loss per share of common stock, basic and diluted (shares)	46,228	40,629	39,438