Note 10 - Retirement Plan (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 1,829	$ 1,416	$ 1,062
Maximum [Member]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	50.00%