Other Income (Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other Income and Expenses [Abstract]
Interest income	$ 5,453	$ 3,664	$ 10,134	$ 4,870
Interest expense	(4,169)	(4,324)	(8,879)	(5,041)
Interest expense-nonrecourse liability related to sale of future royalties	(1,136)	(1,204)	(2,296)	(1,905)
Total	148	(1,864)	(1,041)	(2,076)
Non-cash interest expense	$ 3,900	$ 3,700	$ 7,748	$ 4,307