Note 4 - Earnings Per Share - Shares Used in Calculation of Earnings Per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Weighted-average common shares issued (in shares)	7,350,616	7,329,548	7,345,520	7,323,936
Average treasury stock shares (in shares)	(1,557,843)	(1,192,900)	(1,504,763)	(1,058,133)
Weighted-average common shares and common stock equivalents used to calculate basic earnings per share (in shares)	5,792,773	6,136,648	5,840,757	6,265,803
Additional common stock equivalents (stock options and restricted stock) used to calculate diluted earnings per share (in shares)	13,026	20,533	13,026	21,753
Weighted-average common shares and common stock equivalents used to calculate diluted earnings per share (in shares)	5,805,799	6,157,181	5,853,783	6,287,556