Consolidated Statement of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total revenue	$ 37,632	$ 22,874	$ 17,585
Cost of Goods Sold:
Total Costs of Goods Sold and Services	19,684	12,887	9,837
Gross profit	17,948	9,987	7,748
Operating Expense:
Research and development (including stock compensation of $513, $180, and $59 for the years ended December 31, 2018, and 2017, and 2016, respectively)	15,805	16,304	16,993
Selling, general and administrative (including stock compensation of $4,143, $1,912, and $851 for the years ended December 31, 2018, 2017, and 2016, respectively)	33,693	19,688	12,466
Total operating expenses	49,498	35,992	29,459
Loss from operations	(31,550)	(26,005)	(21,711)
Interest income (expense), net	46	(951)	(1,298)
Other (expense) income, net	(7)	(63)	(164)
Loss before income taxes	(31,511)	(27,019)	(23,173)
Income tax provision	(25)
Net loss	(31,536)	(27,019)	(23,173)
Reconciliation of net loss to net loss attributable to common stockholders:
Net loss	(31,536)	(27,019)	(23,173)
Accretion of preferred stock to redemption value		(4,110)	(4,437)
Accrued dividends on preferred stock		(59)	(8)
Net loss attributable to common stockholders	$ (31,536)	$ (31,188)	$ (27,618)
Net loss per share attributable to common stockholders, basic and diluted	$ (1.43)	$ (8.30)	$ (12.89)
Weighted-average common shares outstanding, basic and diluted	21,994,317	3,756,954	2,142,840
Product revenue
Total revenue	$ 23,365	$ 14,124	$ 10,601
Cost of Goods Sold:
Total Costs of Goods Sold and Services	12,729	7,742	6,299
Service and other revenue
Total revenue	12,117	7,676	5,012
Cost of Goods Sold:
Total Costs of Goods Sold and Services	6,955	5,145	3,163
Collaboration and license revenue
Total revenue	$ 2,150	$ 1,074	1,972
Cost of Goods Sold:
Total Costs of Goods Sold and Services			$ 375