Note 2 - Summary of Significant Accounting Policies - Reconciliation of Net Income and Number of Shares Used in Computations of Basic and Diluted EPS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Net income	$ 3,000,000	$ 3,625,000
Shares (denominator):
Basic weighted average common shares outstanding (in shares)	13,142,872	13,909,688
Add: Dilutive effect of common stock options (in shares)	25,853	53,131
Diluted weighted average common shares outstanding (in shares)	13,168,725	13,962,819
Earnings per common share:
Basic earnings per common share (in dollars per share)	$ 0.23	$ 0.26
Diluted earnings per common share (in dollars per share)	$ 0.23	$ 0.26