Note 4 - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share [Abstract]
Numerator for basic and diluted earnings per share - net income	$ 4,118	$ 3,710
Denominator for basic earnings per share - weighted average shares outstanding	3,588,363	3,552,854
Effect of dilutive securities - employee stock options		1,602
Denominator for diluted earnings per share - adjusted weighted average shares outstanding	3,588,363	3,554,456
Earnings per share - basic	$ 1.15	$ 1.04
Earnings per share - diluted	$ 1.15	$ 1.04