Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accrued Expenses
Employee compensation expenses	$ 2,489	$ 3,321
Research and development expenses	1,134	2,857
Professional fees	112	168
Payable to EPI Health	4,950
Other	659	1,375
Total accrued expenses	$ 9,344	$ 7,721