Note 3 - Summary of Significant Accounting Policies - Reconciliation of Net Income and Number of Shares Used in Computers of Basic and Diluted EPS (Details) - USD ($)	3 Months Ended						12 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Net income	$ 1,430,000	$ 1,146,000	$ 552,000	$ 503,000	$ 693,000	$ 1,522,000	$ 4,189,000	$ 3,282,000
Basic weighted average common shares outstanding (in shares)							11,856,356	12,713,533
Add: Dilutive effect of common stock options (in shares)							0	67,471
Diluted weighted average common shares outstanding (in shares)							11,856,356	12,781,004
Basic earnings per common share (in dollars per share)							$ 0.35	$ 0.26
Diluted earnings per common share (in dollars per share)							$ 0.35	$ 0.26