Accrued Expenses and Long-Term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current accrued expenses
Accrued payroll and other employee benefits	$ 2,036	$ 2,938
Accrued clinical trial related costs	4,858	4,729
Accrued other	2,940	3,259
Current accrued expenses	$ 9,834	$ 10,926