Note 11 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 11,000
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	(0)	$ 1,620	$ (0)
Unrecognized Tax Benefits, Ending Balance	141	0	$ 1,512	$ 1,363
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%	21.00%
Impact of 382 Ownership Changes [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ (65,600)
Research Tax Credit Carryforward [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(7,200)
Increase (Decrease) in Tax Credit Carryforward	(7,200)
Assessment of Net Operating Loss [Member]
Write-down of Operating Loss Carryforward	58,400
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(58,400)
Domestic Tax Authority [Member]
Increase (Decrease) in Operating Loss Carryforwards	(253,000)
Operating Loss Carryforwards, Total	397,200
Operating Loss Carryforwards, Subject to Expiration	254,500
Operating Loss Carryforwards, Not Subject to Expiration	142,700
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	9,400
State and Local Jurisdiction [Member]
Increase (Decrease) in Operating Loss Carryforwards	(204,000)
Operating Loss Carryforwards, Total	309,200
Operating Loss Carryforwards, Subject to Expiration	299,900
Operating Loss Carryforwards, Not Subject to Expiration	9,300
Foreign Tax Authority [Member] | Ministry of Economic Affairs and Finance, Italy [Member]
Operating Loss Carryforwards, Total	25,200
Foreign Tax Authority [Member] | Luxembourg Inland Revenue [Member]
Operating Loss Carryforwards, Subject to Expiration	96,600
Foreign Tax Authority [Member] | Swiss Federal Tax Administration (FTA) [Member]
Operating Loss Carryforwards, Subject to Expiration	90,600
Foreign Tax Authority [Member] | Canada Revenue Agency [Member]
Operating Loss Carryforwards, Subject to Expiration	$ 500