Note 7 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%
Deemed Dividend Paid by Foreign Subsidiary	$ 9,600,000		$ 3,000,000
Provisional Tax Expense (Benefit) for Global Intangible Low Taxed Income	10,000	$ 13,000	40,000
Cumulative Tax Incentives	435,000	1,900,000
Income Tax Credits and Adjustments	45,000	24,000	0
Change in Tax Law, Deferral of Social Security Tax Payments	1,323,000
Deferred Tax Asset, Prior Year Foreign Tax Credit Carryforwards, Write Off	535,000
Unrecognized Tax Benefits, Ending Balance	768,000	592,000	$ 554,000
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	15,000	7,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 668,000	$ 515,000