Note 9 - 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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net income	$ 1,010,000	$ 959,000	$ 2,228,000	$ 1,467,000
Shares (denominator):
Basic weighted average common shares outstanding (in shares)	13,184,321	14,086,277	13,287,583	14,151,734
Add: dilutive effect of common stock options (in shares)	23,817	41,657	58,563	67,329
Diluted weighted average common shares outstanding (in shares)	13,208,138	14,127,934	13,346,146	14,219,063
Earnings per common share:
Basic (in dollars per share)	$ 0.08	$ 0.07	$ 0.17	$ 0.10
Diluted (in dollars per share)	$ 0.08	$ 0.07	$ 0.17	$ 0.10