Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accrued Liabilities, Current [Abstract]
Accrued payroll and related expenses	$ 3,647	$ 4,037
Accrued preclinical, manufacturing and clinical expenses	6,600	4,230
Accrued professional fees and insurance	861	675
Accrued other	65	44
Total	$ 11,173	$ 8,986