Note 2 - Earnings Per Common Share - Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net income	$ 8,437	$ 8,790	$ 8,410	$ 25,161	$ 26,955
Basic earnings per common share - weighted-average shares (in shares)	32,531		33,622	32,476	33,555
Effect of dilutive stock options (in shares)	184		224	177	261
Diluted earnings per common share - weighted-average shares and assumed conversions (in shares)	32,715		33,846	32,653	33,816
Basic earnings per common share (in dollars per share)	$ 0.26		$ 0.25	$ 0.77	$ 0.80
Diluted earnings per common share (in dollars per share)	$ 0.26		$ 0.25	$ 0.77	$ 0.80