Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Product	$ 20,555	$ 9,620	$ 5,988
Service	1,504	530	411
Distribution rights	178
Grant		240
Total revenue	22,237	10,390	6,399
Cost of revenue:
Product	23,897	12,673	8,176
Service	1,969	1,871	975
Total cost of revenue	25,866	14,544	9,151
Gross margin	(3,629)	(4,154)	(2,752)
Operating expenses:
Research and development	11,442	10,449	9,404
Selling and marketing	5,601	5,139	4,681
General and administrative	23,503	21,685	14,742
Total operating expenses	40,546	37,273	28,827
Loss from operations	(44,175)	(41,427)	(31,579)
Interest income	2	2	1
Interest expense	(5,951)	(3,452)	(2,243)
Other (expense) income, net	(512)	(117)	21
Loss before provision for income taxes	(50,636)	(44,994)	(33,800)
Provision for income taxes		1
Net loss	(50,636)	(44,995)	(33,800)
Deemed capital contribution on repurchase of Series A preferred stock			9
Net loss attributable to common stockholders	$ (50,636)	$ (44,995)	$ (33,791)
Net loss per share attributable to common stockholders, basic and diluted	$ (1.26)	$ (2.58)	$ (37.87)
Weighted-average common shares used to compute net loss per share attributable to common stockholders, basic and diluted	40,068,307	17,432,434	892,315