Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue:
Product and service	$ 18,045	$ 15,765
Collaboration	5,040	2,298
Total revenue	23,085	18,063
Costs and expenses:
Cost of product and service revenue	7,695	7,163
Research and development	13,832	10,801
Selling, general and administrative	19,437	17,565
Total costs and expenses	40,964	35,529
Loss from operations	(17,879)	(17,466)
Other income (expense):
Interest income	238	147
Interest expense	(1,563)	(1,501)
Other income, net	65	13
Total other income (expense), net	(1,260)	(1,341)
Net loss before provision for income tax	(19,139)	(18,807)
Provision for income tax	(63)	(45)
Net loss	$ (19,202)	$ (18,852)
Net loss per share - basic and diluted (in dollars per share)	$ (0.75)	$ (0.87)
Weighted average shares used in computing basic and diluted net loss per share (in shares)	25,479	21,588