Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Product and service	$ 72,010	$ 69,134	$ 56,639
Collaboration	42,895	17,355	6,028
Total revenue	114,905	86,489	62,667
Costs and expenses:
Cost of product and service revenue	31,880	30,245	26,126
Research and development	46,888	34,720	24,597
Selling, general and administrative	74,334	62,700	53,186
Total costs and expenses	153,102	127,665	103,909
Loss from operations	(38,197)	(41,176)	(41,242)
Other income (expense):
Interest income	809	390	233
Interest expense	(6,153)	(5,672)	(4,017)
Other income (expense)	183	(515)	(389)
Total other income (expense)	(5,161)	(5,797)	(4,173)
Net loss before provision for income taxes	(43,358)	(46,973)	(45,415)
Provision for income taxes	(204)	(116)	(166)
Net loss	$ (43,562)	$ (47,089)	$ (45,581)
Net loss per share-basic and diluted (in dollars per share)	$ (1.84)	$ (2.34)	$ (2.40)
Weighted average shares used in computing basic and diluted net loss per share (in shares)	23,731	20,116	19,027