Accrued Expenses and Other Payables (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accrued Expenses and Other Payables
Accrued clinical and research related expenses	$ 9,424	$ 7,232
Accrued employee related expenses	2,808	4,637
Accrued professional service fees	649	301
Accrued interest payable		68
Other	36	122
Total accrued expenses and other payables	$ 12,917	$ 12,360