Note 12 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Expense (Benefit), Total	$ 0	$ 0
Gross Net Operating Loss Carryforwards	52,700
Deferred Tax Assets, Valuation Allowance	19,327	14,937
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ 4,390	$ 4,903
Unrecognized Tax Benefits, Ending Balance	0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	0
Domestic Tax Authority [Member]
Operating Loss Carryforwards	$ 99,047
Domestic Tax Authority [Member] | Earliest Tax Year [Member]
Operating Loss Carryforwards, Expiration Year	2029
Domestic Tax Authority [Member] | Latest Tax Year [Member]
Operating Loss Carryforwards, Expiration Year	2038
Foreign Tax Authority [Member]
Operating Loss Carryforwards	$ 1,514