Note 5 - Net Income Per Common Share - Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net income, basic and diluted	$ 4,482	$ 3,556	$ 7,811	$ 9,736
Average common shares issued and outstanding, basic and diluted (in shares)	7,512	7,502	7,511	7,501
Net income per common share, basic and diluted (in dollars per share)	$ 0.60	$ 0.47	$ 1.04	$ 1.30