Supplementary Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Product sales, net	$ 39,390	$ 30,499	$ 26,151	$ 21,810	$ 31,335	$ 22,484	$ 19,011	$ 18,027	$ 117,850	$ 90,857	$ 62,760
Gross profit	28,805	21,175	17,129	13,170	22,706	14,346	11,284	10,361	80,279	58,697	33,570
Income (loss) from operations	9,210	3,097	(20,200)	(3,358)	5,995	(1,336)	(4,246)	(4,322)	(11,251)	(3,909)	(14,984)
Net (loss) income	$ 9,501	$ 3,470	$ (19,792)	$ (2,844)	$ 5,242	$ (1,069)	$ (4,651)	$ (7,659)	$ (9,665)	$ (8,137)	$ (17,286)
Net (loss) income per share (Basic) (in USD per share)	$ 0.21	$ 0.08	$ (0.45)	$ (0.07)	$ 0.12	$ (0.02)	$ (0.12)	$ (0.21)	$ (0.22)	$ (0.20)
Net (loss) income per share (Diluted) (in USD per share)	$ 0.20	$ 0.07	$ (0.45)	$ (0.07)	$ 0.11	$ (0.02)	$ (0.12)	$ (0.21)	$ (0.22)	$ (0.20)