Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued Liabilities Current [Abstract]
Payroll and employee-related costs	$ 15,229	$ 7,321
Research costs	9,434	7,973
Licensing fees	750	625
Professional fees	2,040	1,848
Intellectual property costs	2,311	2,193
Accrued property and equipment	407	294
Other	9	598
Total	$ 30,180	$ 20,852