Note 8 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Federal Income Tax Expense (Benefit), Continuing Operations, Total	$ 0	$ 0
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate (Negative Rate), Percent	21.00%	21.00%
Deferred Tax Assets, Operating Loss Carryforwards, Total	$ 326,000
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	60,000
Unrecognized Tax Benefits, Period Increase (Decrease), Total	$ 0	$ 0