Product Revenue and Concentration of Credit Risks - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Net product sales	$ 21,398	$ 1,520	$ 51,269	$ 1,520
Fintepla
Disaggregation of Revenue [Line Items]
Net product sales	$ 21,400		$ 51,300
Geographic Concentration Risk | Accounts Receivable | U.S. customer
Disaggregation of Revenue [Line Items]
Concentration of credit risk and major customers (percent)	80.00%		80.00%
Geographic Concentration Risk | Product revenue | U.S. customer
Disaggregation of Revenue [Line Items]
Concentration of credit risk and major customers (percent)	80.00%		80.00%
United States | Fintepla
Disaggregation of Revenue [Line Items]
Net product sales	$ 18,400	$ 1,500	$ 45,300	$ 1,500