Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue:
Product and service	$ 16,915	$ 19,167	$ 50,990	$ 48,791
Collaboration	10,101	4,766	28,682	12,466
Total revenue	27,016	23,933	79,672	61,257
Costs and expenses:
Cost of product and service revenue	7,305	8,075	22,692	21,816
Research and development	11,374	8,717	33,213	24,724
Selling, general and administrative	18,380	15,607	54,590	46,018
Total costs and expenses	37,059	32,399	110,495	92,558
Loss from operations	(10,043)	(8,466)	(30,823)	(31,301)
Other income (expense):
Interest income	252	104	549	266
Interest expense	(1,556)	(1,509)	(4,585)	(4,150)
Other income (expense), net	(12)	(179)	185	(238)
Total other income (expense), net	(1,316)	(1,584)	(3,851)	(4,122)
Net loss before provision for income tax	(11,359)	(10,050)	(34,674)	(35,423)
Provision for income tax	(45)	(38)	(137)	(73)
Net loss	$ (11,404)	$ (10,088)	$ (34,811)	$ (35,496)
Net loss per share - basic and diluted (in dollars per share)	$ (0.45)	$ (0.51)	$ (1.50)	$ (1.79)
Weighted average shares used in computing basic and diluted net loss per share (in shares)	25,240	19,864	23,172	19,779