Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Total revenues	$ 60,594	$ 50,024	$ 48,837
Costs and operating expenses:
Cost of product revenue	12,620	14,327	9,753
Research and development	29,978	29,659	22,229
Selling, general and administrative	29,291	29,008	25,419
Total costs and operating expenses	71,889	72,994	57,401
Loss from operations	(11,295)	(22,970)	(8,564)
Interest income	671	147	60
Other expenses, net	(291)	(92)	(94)
Loss before income taxes	(10,915)	(22,915)	(8,598)
Provision for (benefit from) income taxes	(37)	81	(40)
Net loss	$ (10,878)	$ (22,996)	$ (8,558)
Net loss per share, basic and diluted (usd per share)	$ (0.21)	$ (0.50)	$ (0.21)
Weighted average common stock shares used in computing net loss per share, basic and diluted (shares)	52,205	46,228	40,629
Product Sales
Revenues:
Total revenues	$ 25,590	$ 26,685	$ 15,321
Research and Development Revenues
Revenues:
Total revenues	$ 35,004	$ 23,339	$ 33,516