Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued Expenses
Accrued compensation	$ 1,365	$ 1,241
Accrued contracted research costs	737	680
Accrued professional fees	370	393
Accrued other	98	109
Accrued franchise tax	40	168
Accrued severance		172
Total	$ 2,610	$ 2,763