Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accrued Expenses
Payroll and related costs	$ 1,746	$ 1,364
Clinical studies and drug development	2,422	2,781
Professional fees	379	204
Short-term lease liabilities	430
Other	33	88
Total accrued expenses	$ 5,010	$ 4,437