Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued Expenses
Payroll and related costs	$ 2,179	$ 1,962
Clinical and nonclinical trial expenses	4,199	3,958
Professional and consulting fees	859	605
Restructuring expenses	113	1,147
Other	111	212
Total accrued expenses	$ 7,461	7,884
Salary continuation severance benefits		$ 700