Note 12 - Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Stock-based compensation	$ 3,119	$ 2,840
Accrued expenses and other	2,666	2,538
Research credit carryforward	2,859	1,341
Fixed Assets	319	162
Net operating loss carryforwards	93,332	83,908
Deferred Tax Assets, Gross	112,003	96,092
Valuation Allowance	(110,511)	(94,704)
Net deferred tax asset	1,492	1,388
Fixed assets and other	(1,448)	(1,214)
Net deferred tax liability	(1,448)	(1,214)
Net deferred tax asset (liability)	44	174
Start-up Costs and Other Intangibles [Member]
Capitalized costs	644	921
Research Tax Credit Carryforward [Member]
Capitalized costs	$ 9,064	$ 4,382