Note 9 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	35.00%
Provisional Tax Expense (Benefit) for Tax Cuts and Jobs Act		$ (1,900,000)
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	150,000
Provisional Tax Expense (Benefit) for Global Intangible Low Taxed Income	40,000
Unrecognized Tax Benefits, Ending Balance	554,000	843,000	$ 662,000
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	6,000	5,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 482,000	$ 620,000