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, 2018	Dec. 31, 2017
Net income	$ 3,625,000	$ 2,633,000
Shares (denominator):
Basic weighted average common shares outstanding (in shares)	13,909,688	14,825,600
Add: Dilutive effect of common stock options (in shares)	53,131	167,409
Diluted weighted average common shares outstanding (in shares)	13,962,819	14,993,009
Earnings per common share:
Basic earnings per common share (in dollars per share)	$ 0.26	$ 0.18
Diluted earnings per common share (in dollars per share)	$ 0.26	$ 0.18