Accrued Expenses - Components of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued clinical	$ 54,581	$ 61,815
Product revenue allowances	31,225	30,552
Accrued payroll	7,727	12,604
MTPC - Supply of Validation Drug Product	6,441
Lease liability	5,096	4,989
Professional fees	3,949	3,444
Accrued commercial manufacturing	2,694	2,680
Royalties	2,459	2,713
Accrued severance	452	725
Accrued other	10,263	9,549
Total accrued expenses	$ 124,887	$ 129,071