Liability Related to Sale of Future Royalties - Rollforward of Liability Related to Sale of Future Royalties (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Contractual Arrangement, Royalties Agreement, Liability, Noncurrent [Roll Forward]
Liability related to sale of future royalties, net beginning balance at December 31, 2021	$ 53,079
MTPC royalties payable	(329)
Non-cash interest expense recognized	2,345	$ 2,162
Liability related to sale of future royalties, net — ending balance	$ 55,095