Note 2 - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2022		Sep. 30, 2022		Jun. 30, 2022		Mar. 31, 2022		Dec. 31, 2021		Sep. 30, 2021		Jun. 30, 2021		Mar. 31, 2021		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Numerator for basic and diluted earnings per share - net income	$ 5,447		$ 3,415		$ 3,349		$ 3,710		$ 4,149		$ 3,424		$ 3,869		$ 5,050		$ 15,921	$ 16,492	$ 12,083
Denominator for basic earnings per share - weighted average shares outstanding																	3,564,481	3,553,949	3,537,323
Effect of dilutive securities - employee stock options																		189	37
Denominator for diluted earnings per share - adjusted weighted average shares outstanding																	3,564,481	3,554,138	3,537,360
Earnings per share - basic	$ 1.52	[1]	$ 0.96	[1]	$ 0.94	[1]	$ 1.04	[1]	$ 1.17	[1]	$ 0.96	[1]	$ 1.09	[1]	$ 1.42	[1]	$ 4.47	$ 4.64	$ 3.42
Earnings per share - diluted	$ 1.52	[1]	$ 0.96	[1]	$ 0.94	[1]	$ 1.04	[1]	$ 1.17	[1]	$ 0.96	[1]	$ 1.09	[1]	$ 1.42	[1]	$ 4.47	$ 4.64	$ 3.42

[1] Due to rounding, quarterly earnings per share may not sum to annual earnings per share