Note 15 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Expense (Benefit), Total	$ (0)	$ 0
Deferred Tax Assets, Valuation Allowance	28,013	$ 18,113
Deferred Tax Assets, Capitalized Research and Development Expenses	28,600
Deferred Tax Assets, Amortized Research and Development Expenses	1,800
Unrecognized Tax Benefits, Ending Balance	0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total	0
Domestic Tax Authority [Member]
Operating Loss Carryforwards	59,100
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	1,400
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	42,500
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	$ 2,400