Note 13 - Income Tax (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Effective Income Tax Rate Reconciliation, Percent, Total	(105.70%)	(7.10%)
Deferred Tax Assets, Valuation Allowance, Total	$ 14,700	$ 16,682
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(2,000)	2,900
Research and Development Tax Credit Carryforwards Offset by Reserve for Uncertain Tax Positions	1,000
Deferred Tax Assets, Tax Credit Carryforwards, Total	2,900
Cash and Cash Equivalents, at Carrying Value, Ending Balance	7,821	8,317
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	1,300
Tax Cuts and Jobs Act, Change in Tax Rate Operating Loss Carryforwards From Acquisition, CARES Act	5,300
Deferred Tax Assets, Valuation Allowance, Increase (Decrease) Due to Change in Tax Rate Operating Loss Carryforward From Acquisition CARES Act	1,100
Non-US [Member] | Subsidiaries [Member]
Cash and Cash Equivalents, at Carrying Value, Ending Balance	2,800	2,500
Expire in 2022 [Member]
Deferred Tax Assets, Tax Credit Carryforwards, Research	8,400
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 200
Domestic Tax Authority [Member]
Open Tax Year	2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards, Total	$ 22,700
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Expire between 2029 and 2037 [Member]
Operating Loss Carryforwards, Total	22,600
State and Local Jurisdiction [Member] | Expire between 2022 and 2041 [Member]
Operating Loss Carryforwards, Total	16,400
Foreign Tax Authority [Member]
Operating Loss Carryforwards, Total	$ 9,900
Open Tax Year	2017 2018 2019 2020 2021
UK Pension Liability [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ (900)
UK Pension Asset [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ 700