Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued Liabilities
Employee bonuses	$ 1,437	$ 621
Accrued retention bonus		638
Accrued professional fees and other	367	84
Total accrued liabilities	$ 1,804	$ 1,343