Note 12 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 16,400
Unrecognized Tax Benefits, Ending Balance	335	$ 141	$ 0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	$ 0	$ 0
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%
Domestic Tax Authority [Member]
Increase (Decrease) in Operating Loss Carryforwards	$ (253,000)
Operating Loss Carryforwards	419,400
Operating Loss Carryforwards, Subject to Expiration	254,500
Operating Loss Carryforwards, Not Subject to Expiration	164,900
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	10,200
Increase (Decrease) in Tax Credit Carryforward	(8,800)
Domestic Tax Authority [Member] | Impact of 382 Ownership Changes [Member]
Increase (Decrease) in Operating Loss Carryforwards	(253,000)
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	328,900
Operating Loss Carryforwards, Subject to Expiration	317,400
Operating Loss Carryforwards, Not Subject to Expiration	11,500
State and Local Jurisdiction [Member] | Impact of 382 Ownership Changes [Member]
Increase (Decrease) in Operating Loss Carryforwards	(204,000)
Foreign Tax Authority [Member] | Ministry of Economic Affairs and Finance, Italy [Member]
Operating Loss Carryforwards	24,600
Foreign Tax Authority [Member] | Luxembourg Inland Revenue [Member]
Operating Loss Carryforwards, Subject to Expiration	95,900
Foreign Tax Authority [Member] | Swiss Federal Tax Administration (FTA) [Member]
Operating Loss Carryforwards, Subject to Expiration	116,500
Foreign Tax Authority [Member] | Canada Revenue Agency [Member]
Operating Loss Carryforwards, Subject to Expiration	$ 900