Note 8 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Expense (Benefit), Total	$ 1,780	$ 2,140	$ 5,490	$ 7,090
Effective Income Tax Rate Reconciliation, Percent, Total	17.80%	17.70%	19.10%	19.90%
Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-based Payment Arrangement, Amount	$ (800)		$ (800)
Income Tax Expense Related to Termination of Defined Benefit Plan	$ (600)		$ (600)