Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 56,734,000	$ 37,632,000	$ 22,874,000
Cost of goods sold:
Total costs of goods sold and services	29,898,000	19,684,000	12,887,000
Gross profit	26,836,000	17,948,000	9,987,000
Operating expense:
Research and development (including stock compensation of $718, $513, and $180 for the years ended December 31, 2019, 2018, and 2017, respectively)	16,190,000	15,805,000	16,304,000
Selling, general and administrative (including stock compensation of $5,346, $4,143, and $1,912 for the years ended December 31, 2019, 2018, and 2017, respectively)	52,246,000	33,693,000	19,688,000
Total operating expenses	68,436,000	49,498,000	35,992,000
Loss from operations	(41,600,000)	(31,550,000)	(26,005,000)
Interest income (expense), net	627,000	46,000	(951,000)
Other income (expense), net	(10,000)	(7,000)	(63,000)
Loss before income tax	(40,983,000)	(31,511,000)	(27,019,000)
Income tax provision	187,000	(25,000)	0
Net loss	(40,796,000)	(31,536,000)	(27,019,000)
Reconciliation of net loss to net loss attributable to common stockholders:
Net loss	(40,796,000)	(31,536,000)	(27,019,000)
Accretion of preferred stock to redemption value			(4,110,000)
Accrued dividends on preferred stock			(59,000)
Net loss attributable to common stockholders	$ (40,796,000)	$ (31,536,000)	$ (31,188,000)
Net loss per share, basic and diluted	$ (1.63)	$ (1.43)	$ (8.30)
Weighted-average common shares outstanding, basic and diluted	25,090,708	21,994,317	3,756,954
Product revenue
Revenue	$ 40,491,000	$ 23,365,000	$ 14,124,000
Cost of goods sold:
Total costs of goods sold and services	20,900,000	12,729,000	7,742,000
Service and other revenue
Revenue	16,059,000	12,117,000	7,676,000
Cost of goods sold:
Total costs of goods sold and services	8,998,000	6,955,000	5,145,000
Collaboration and license revenue
Revenue	$ 184,000	$ 2,150,000	$ 1,074,000