Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue:
Revenue	$ 125,568	$ 106,732	$ 114,905
Total revenue	125,568	106,732	114,905
Costs and expenses:
Cost of product and service revenue	44,039	36,331	31,880
Research and development	68,035	61,599	46,888
Selling, general and administrative	96,195	78,195	74,334
Total costs and expenses	208,269	176,125	153,102
Loss from operations	(82,701)	(69,393)	(38,197)
Other income (expense):
Gain on sale of business, net	48,871	0	0
Interest income	2,819	1,331	809
Interest expense	(8,487)	(7,431)	(6,153)
Other income (expense), net	(929)	(1,658)	183
Total other income (expense), net	42,274	(7,758)	(5,161)
Net loss before provision for income taxes	(40,427)	(77,151)	(43,358)
Provision for income taxes	(269)	(249)	(204)
Net loss	$ (40,696)	$ (77,400)	$ (43,562)
Net loss per share-basic and diluted (in dollars per share)	$ (1.18)	$ (2.78)	$ (1.84)
Weighted average shares used in computing basic and diluted net loss per share (in shares)	34,588	27,883	23,731