Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Other Income and Expenses [Abstract]
Interest expense	$ (4,945)	$ (4,546)	$ (14,430)	$ (13,518)
Interest expense on nonrecourse liability related to sale of future royalties	(1,143)	(1,116)	(3,228)	(3,412)
Total	(6,088)	(5,662)	(17,658)	(16,930)
Non-cash interest expense	$ 4,200	$ 4,000	$ 12,351	$ 11,701