Note 5 - Leases - Supplemental Balance Sheet Information Related to Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Operating lease right-of-use assets, net	$ 290	$ 429
Current lease liabilities	274	432
Office Leases [Member]
Operating lease right-of-use assets, net	290	429
Current lease liabilities	$ 274	$ 432