Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Prepaid expenses and other current assets:
Prepaid contract research organization expenses	$ 1,356	$ 1,064
Prepaid insurance	190	58
Other current assets	165	147
Total prepaid expenses and other current assets	1,711	1,269
Accrued and other liabilities:
Accrued professional services	1,432	3,095
Payroll and benefits	1,021	1,146
Taxes	373
Equity transaction related liability	211
Customer Deposits	202
Accrued insurance premium	87
Other	495	588
Total accrued liabilities and other liabilities	$ 3,821	$ 4,829