Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accrued Expenses
Payroll and related costs	$ 1,323	$ 880
Clinical trials and drug development	156	681
Professional fees	113	101
Other	25	113
Total accrued expenses	$ 1,617	$ 1,775