Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accrued Expenses
Accrued contracted research costs	$ 919	$ 680
Accrued compensation	1,033	1,241
Accrued professional fees	388	393
Accrued other	106	172
Accrued franchise tax	30	168
Accrued severance		109
Total	$ 2,476	$ 2,763