Note 5 - Net Income Per Common Share - Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net income, basic and diluted	$ 4,324,000	$ 3,832,000	$ 14,060,000	$ 11,408,000
Less preferred stock dividends	0	0	0	395,000
Net income available to common shareholders, basic and diluted	$ 4,324,000	$ 3,832,000	$ 14,060,000	$ 11,013,000
Average common shares issued and outstanding, basic and diluted (in shares)	7,505	7,495	7,503	7,492
Net income per common share, basic and diluted (in dollars per share)	$ 0.58	$ 0.51	$ 1.87	$ 1.47