Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 21,133	$ 20,067	$ 15,094	$ 18,933	$ 18,634	$ 17,026	$ 14,928	$ 12,766	$ 75,227	$ 63,354	$ 34,557
Gross profit	15,916	14,579	9,758	13,683	13,913	12,856	11,231	9,427	53,936	47,427	23,683
Net loss	$ (16,756)	$ (10,315)	$ (10,353)	$ (9,941)	$ (8,291)	$ (8,007)	$ (11,959)	$ (24,158)	$ (47,365)	$ (52,415)	$ (37,630)
Net loss per share, basic and diluted (in USD per share)	$ (0.49)	$ (0.31)	$ (0.32)	$ (0.32)	$ (0.27)	$ (0.26)	$ (0.42)	$ (20.12)	$ (1.44)	$ (2.28)	$ (39.16)