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Note 8 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Effective Income Tax Rate Reconciliation, Percent, Total	22.90%	8.40%
Deferred Tax Assets, Valuation Allowance, Total	$ 0
Unrecognized Tax Benefits, Ending Balance	$ 0
General Business Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount			$ 1,907
Domestic Tax Authority [Member] \| Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards, Total			$ 58,400
Open Tax Year	2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2012 2013 2014 2015 2016 2017 2018 2019
Foreign Tax Authority [Member]
Open Tax Year	2010 2011 2012 2013 2014 2015 2016 2017 2018 2019
Foreign Tax Authority [Member] \| Her Majesty's Revenue and Customs (HMRC) [Member]
Operating Loss Carryforwards, Total	$ 10,000
State and Local Jurisdiction [Member]
Open Tax Year	2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2012 2013 2014 2015 2016 2017 2018 2019