Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued clinical trial costs	$ 6,264	$ 13,285
Accrued compensation	14,892	11,223
Accrued professional fees	2,627	3,936
Accrued royalties	14,678	0
Other accrued expenses	17,828	5,861
Accrued expenses and other current liabilities	$ 56,289	$ 34,305