Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue:
Product and service	$ 18,310	$ 17,488	$ 34,075	$ 29,624
Collaboration	16,282	5,139	18,581	7,700
Total revenue	34,592	22,627	52,656	37,324
Costs and expenses:
Cost of product and service revenue	8,224	7,871	15,387	13,741
Research and development	11,038	8,799	21,839	16,007
Selling, general and administrative	18,644	15,507	36,210	30,411
Total costs and expenses	37,906	32,177	73,436	60,159
Loss from operations	(3,314)	(9,550)	(20,780)	(22,835)
Other income (expense):
Interest income	150	94	297	162
Interest expense	(1,528)	(1,326)	(3,029)	(2,641)
Other income (expense), net	184	12	197	(59)
Total other income (expense), net	(1,194)	(1,220)	(2,535)	(2,538)
Net loss before provision for income tax	(4,508)	(10,770)	(23,315)	(25,373)
Provision for income tax	(47)	(35)	(92)	(35)
Net loss	$ (4,555)	$ (10,805)	$ (23,407)	$ (25,408)
Net loss per share - basic and diluted (in dollars per share)	$ (0.20)	$ (0.55)	$ (1.06)	$ (1.29)
Weighted average shares used in computing basic and diluted net loss per share (in shares)	22,672	19,803	22,121	19,736