Note 8 - Basic and Diluted Earnings Per Common Share - Reconciliation of Net Income and Number of Shares Used in Computations of Basic and Diluted EPS (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Net income	$ 503,000	$ 693,000	$ 1,522,000	$ 766,000	$ 1,671,000	$ 3,719,000	$ 2,718,000	$ 6,156,000
Shares (denominator):
Basic weighted average common shares outstanding (in shares)	12,615,187			13,177,520			12,834,505	13,255,125
Add: dilutive effect of common stock options (in shares)	73,194			241,965			75,365	300,800
Diluted weighted average common shares outstanding (in shares)	12,688,381			13,419,485			12,909,870	13,555,925
Earnings per common share:
Basic earnings per common share (in dollars per share)	$ 0.04			$ 0.06			$ 0.21	$ 0.46
Diluted earnings per common share (in dollars per share)	$ 0.04			$ 0.06			$ 0.21	$ 0.45