Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue:
Product and service	$ 20,384	$ 18,310	$ 38,429	$ 34,075
Collaboration	4,615	16,282	9,655	18,581
Total revenue	24,999	34,592	48,084	52,656
Costs and expenses:
Cost of product and service revenue	8,552	8,224	16,247	15,387
Research and development	14,585	11,038	28,417	21,839
Selling, general and administrative	20,649	18,644	40,086	36,210
Total costs and expenses	43,786	37,906	84,750	73,436
Loss from operations	(18,787)	(3,314)	(36,666)	(20,780)
Other income (expense):
Interest income	204	150	442	297
Interest expense	(1,604)	(1,528)	(3,167)	(3,029)
Other income (expense), net	(349)	184	(284)	197
Total other income (expense), net	(1,749)	(1,194)	(3,009)	(2,535)
Net loss before provision for income tax	(20,536)	(4,508)	(39,675)	(23,315)
Provision for income tax	(65)	(47)	(128)	(92)
Net loss	$ (20,601)	$ (4,555)	$ (39,803)	$ (23,407)
Net loss per share - basic and diluted (in dollars per share)	$ (0.80)	$ (0.20)	$ (1.55)	$ (1.06)
Weighted average shares used in computing basic and diluted net loss per share (in shares)	25,757	22,672	25,619	22,121