Note 16 - Income Taxes (Details Textual) - USD ($) Pure in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, Percent, Total	0.00%	0.00%
Deferred Tax Assets, Valuation Allowance	$ 83,000	$ 64,273
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	18,727
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	$ 243,453	173,401
Federal Net Operating Loss Carryforwards, Expiration Period Minimum (Year)	5 years
Federal Tax Credit Carry Forward, Expiration Period, Minimum (Year)	5 years
Federal Tax Credit CarryForward, Expiration Period, Maximum (Year)	20 years
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total	$ 0	0
State Tax Credit Carry Forward, Expiration Period, Minimum (Year)	5 years
State Tax Credit Carry Forward, Expiration Period, Maximum (Year)	20 years
Domestic Tax Authority [Member]
Open Tax Year	2019 2020 2021
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	$ 11,915	$ 10,369
State and Local Jurisdiction [Member]
Open Tax Year	2019 2020 2021
Foreign Tax Authority [Member]
Open Tax Year	2021