Sale of Future Revenue - Royalty Obligation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Sale of Future Revenue [Roll Forward]
Liability related to the sale of future revenue, net at December 31, 2020			$ 48,974
Royalties related to the sale of future revenue	$ 13,287	$ 8,260	39,754	$ 38,700
Amortization of issuance costs			110
Interest expense related to the sale of future revenue			10,457	$ 0
Liability related to the sale of future revenue, net (includes current portion of $1,848)	58,464		58,464
Current portion	$ 1,848		1,848
Royalty
Sale of Future Revenue [Roll Forward]
Royalties related to the sale of future revenue			$ (1,077)