Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Revenue	$ 30,604	$ 28,616	$ 88,637	$ 76,700
Costs and expenses:
Cost of product and service revenue	10,925	9,291	29,239	25,538
Research and development	17,007	16,651	50,063	45,068
Selling, general and administrative	23,382	17,810	69,317	57,897
Total costs and expenses	51,314	43,752	148,619	128,503
Loss from operations	(20,710)	(15,136)	(59,982)	(51,803)
Other income (expense):
Interest income	763	384	2,114	826
Interest expense	(2,415)	(1,631)	(6,052)	(4,798)
Other expense, net	(322)	(46)	(552)	(330)
Total other expense, net	(1,974)	(1,293)	(4,490)	(4,302)
Net loss before provision for income tax	(22,684)	(16,429)	(64,472)	(56,105)
Provision for income tax	(64)	(57)	(211)	(185)
Net loss	$ (22,748)	$ (16,486)	$ (64,683)	$ (56,290)
Net loss per share - basic and diluted (in dollars per share)	$ (0.64)	$ (0.56)	$ (1.90)	$ (2.09)
Weighted average shares used in computing basic and diluted net loss per share (in shares)	35,576	29,366	34,121	26,882
Total product and service revenue
Revenue:
Revenue	$ 26,349	$ 21,453	$ 70,069	$ 59,882
Collaboration revenue
Revenue:
Revenue	$ 4,255	$ 7,163	$ 18,568	$ 16,818