Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Total revenue	$ 80,962	$ 34,042	$ 22,237
Cost of revenue:
Total cost of revenue	74,359	27,710	25,866
Gross margin	6,603	6,332	(3,629)
Operating expenses:
Research and development	16,520	14,709	11,442
Selling and marketing	15,062	8,412	5,601
General and administrative	50,113	31,375	23,503
Total operating expenses	81,695	54,496	40,546
Loss from operations	(75,092)	(48,164)	(44,175)
Interest income	8	5	2
Interest expense	(7,701)	(7,247)	(5,951)
Other income (expense), net	6,389	(16,770)	(512)
Loss before provision for income taxes	(76,396)	(72,176)	(50,636)
Provision for income taxes	0	0	0
Net loss and comprehensive loss	(76,396)	(72,176)	(50,636)
Amortization of beneficial conversion feature related to Series A convertible preferred stock	(2,728)	0	0
Net loss attributable to common stockholders, basic and diluted	$ (79,124)	$ (72,176)	$ (50,636)
Net loss per share, basic and diluted	$ (0.98)	$ (1.23)	$ (1.26)
Weighted-average common shares used to compute net loss per share attributable to common stockholders, basic and diluted	81,123,140	58,457,868	40,068,307
Product
Revenue:
Total revenue	$ 76,626	$ 30,458	$ 20,555
Cost of revenue:
Total cost of revenue	66,522	25,488	23,897
Service
Revenue:
Total revenue	3,861	3,109	1,504
Cost of revenue:
Total cost of revenue	7,837	2,222	1,969
Distribution Rights
Revenue:
Total revenue	$ 475	$ 475	$ 178