Note 9 - Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Net operating loss carryforwards	$ 316,962	$ 303,729
Research and development credit	45,806	42,031
Noncash compensation	12,275	10,325
Disallowed interest	3,328	3,882
Capitalized R&D Expenses	36,613	39,411
Other	3,333	985
Deferred tax asset, excluding valuation allowance	418,317	400,363
Less valuation allowance	(418,317)	(400,363)
Net deferred tax assets	$ 0	$ 0