Debt - Long-term debt (Details)	12 Months Ended
	Dec. 31, 2019 USD ($)
Debt
Term Loan	$ 10,000,000
Debt issuance costs, net of amortization	(222,000)
Accrued final payment fee	16,000
Long-term debt, net	$ 9,794,000
Maturity date	Oct. 01, 2023
Annual interest rate	7.85%
Deferred financing cost	$ 235,000
Debt issuance costs amortized and recognized as Interest expense	$ 13,000
Effective interest rate on long-term debt	9.81%