Other Income (Expense), Net - Summary of Other Income (Expense), Net (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other income (expense), net
Investment income		$ 38	$ 104	$ 130	$ 2,660
Interest expense		(1,835)	(1,671)	(5,322)	(13,183)
Non-cash interest expense on liability related to sale of future royalty		(11,958)	(10,413)	(34,312)	(11,077)
Other income (expense)		4	816	(26)	816
Loss on extinguishment of debt	$ (11,200)	0	0	0	(11,183)
Total other income (expense), net		$ (13,751)	$ (11,164)	$ (39,530)	$ (31,967)