Leases - Supplemental balance sheet information (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Leases
Operating lease – right of use assets, net	$ 1,537	$ 1,936
Current portion of operating lease liabilities	623	579
Operating lease liabilities, net of current portion	1,026	1,489
Total operating lease liabilities	$ 1,649	$ 2,068
Weighted average remaining lease term for operating leases (in years)	2 years 7 months 20 days	3 years 6 months 14 days
Weighted average discount rate for operating leases	5.87%	6.10%