Note 8 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unrecognized Tax Benefits, Ending Balance	$ 848	$ 711	$ 525	$ 390
Deferred Tax Assets, Valuation Allowance, Total	1,388	1,255
Deferred Tax Assets, Operating Loss Carryforwards, Total	1,289	1,421
Deferred Tax Assets, Capital Loss Carryforwards	277	279
State and Local Jurisdiction [Member]
Tax Credit Carryforward, Amount	1,500
State and Local Jurisdiction [Member] | Internal Revenue Service (IRS) [Member]
Tax Adjustments, Settlements, and Unusual Provisions			$ 200
Foreign Tax Authority [Member] | AUSTRALIA
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	100	$ (700)
Deferred Tax Assets, Operating Loss Carryforwards, Total	1,200
Deferred Tax Assets, Capital Loss Carryforwards	900
Foreign Tax Authority [Member] | FRANCE
Deferred Tax Assets, Operating Loss Carryforwards, Total	2,500
Foreign Tax Authority [Member] | SPAIN
Deferred Tax Assets, Operating Loss Carryforwards, Total	900
Foreign Tax Authority [Member] | NORWAY
Deferred Tax Assets, Operating Loss Carryforwards, Total	$ 100