Revenue - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue
Product revenue - gross	$ 47,555	$ 17,152	$ 135,490	$ 37,567
Less: Rebate and sales return	(4,452)	(2,501)	(35,349)	(3,703)
Product revenue - net	$ 43,103	$ 14,651	$ 100,141	$ 33,864