Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued Expenses and Other Current Liabilities.
Accrued compensation and benefits	$ 2,490	$ 1,526
Accrued contract manufacturing	1,550	1,003
Accrued clinical	606	752
Accrued professional services	530	672
Accrued research	275	364
Current portion of operating lease liabilities	506
Other	295	529
Total accrued expenses and other current liabilities	$ 6,252	$ 4,846