Other Income (Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other Income and Expenses [Abstract]
Interest income	$ 5,523	$ 4,461	$ 15,657	$ 9,331
Interest expense	(4,546)	(4,374)	(13,425)	(9,415)
Interest expense on nonrecourse liability related to sale of future royalties	(1,116)	(1,191)	(3,412)	(3,096)
Total	(139)	(1,104)	(1,180)	(3,180)
Non-cash interest expense	$ 4,000	$ 3,700	$ 11,701	$ 8,052