Note 2 - Earnings Per Common Share - Basic and Diluted Earnings Per Common Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income	$ 8,357	$ 7,926	$ 18,545	$ 13,213
Basic earnings per common share - weighted-average shares (in shares)	33,582	33,369	33,521	33,355
Effect of dilutive stock options (in shares)	271	327	281	307
Diluted earnings per common share - weighted-average shares and assumed conversions (in shares)	33,853	33,696	33,802	33,662
Basic earnings per common share (in dollars per share)	$ 0.25	$ 0.24	$ 0.55	$ 0.40
Diluted earnings per common share (in dollars per share)	$ 0.25	$ 0.24	$ 0.55	$ 0.39