Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accrued Expenses
Employee compensation expenses	$ 1,419	$ 3,321
Research and development expenses	2,322	2,857
Professional fees	166	168
Payable to EPI Health	5,241
Other	1,226	1,375
Total accrued expenses	$ 10,374	$ 7,721