Note 7 - Leases - Maturities of operating lease liabilities (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Leases [Abstract]
Weighted average remaining lease term	1 year 8 months 12 days
Weighted average discount rate	8.50%
Maturities of operating lease liabilities
2020	$ 117
2021	98
2022	41
Total lease payments	256
Less imputed interest	$ (43)
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:LiabilitiesOtherThanLongtermDebtNoncurrent