Note 8 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Expense (Benefit), Total	$ 960	$ 3,700	$ 3,710	$ 4,950
Effective Income Tax Rate Reconciliation, Percent, Total	17.30%	19.60%	19.80%	21.10%
Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-based Payment Arrangement, Amount	$ (800)
Income Tax Expense Related to Termination of Defined Benefit Plan	$ (600)