Note 7 - Income Taxes (Details Textual) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Deferred Tax Assets, Valuation Allowance	$ 38,637	$ 32,308	$ 25,696
Unrecognized Tax Benefits	339	$ 339	$ 236
Refundable R and D Tax Credit Received	200
Domestic Tax Jurisdiction [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards	61,700
Operating Loss Carryforwards, Subject To Expiration	6,100
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	$ 4,000