Note 7 - Income Taxes (Details Textual)	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Provisional Tax Expense (Benefit) for Tax Cuts and Jobs Act			$ (1,900,000)
Repatriation Tax Payable Over Years			8
Effective Income Tax Rate Reconcilation, Withholding Tax on Repatriation of Foreign Earnings			$ 706,000
Deemed Dividend Paid by Foreign Subsidiary		$ 3,000,000
Payments for Withholding Tax on Repatriation of Foreign Earnings	$ 107,000	150,000
Provisional Tax Expense (Benefit) for Global Intangible Low Taxed Income	13,000	40,000
Cumulative Tax Incentives	1,900,000
Income Tax Credits and Adjustments	$ 24,000	$ 0	$ 4,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	35.00%
Unrecognized Tax Benefits, Ending Balance	$ 592,000	$ 554,000	$ 843,000
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	7,000	6,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 515,000	$ 482,000