Note 13 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-Based Payment Arrangement, Amount	$ 6,400
Income Tax Benefit Due to Research and Development Tax Credits	1,500
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	374	$ 985	$ 1,308
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(5,100)	$ (12,500)
Domestic Tax Authority [Member]
Operating Loss Carryforwards	927,900
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	38,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	865,500
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	$ 24,300