Note 11 - Earnings Per Share - Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Net income	$ 8,868	$ 6,202
Weighted average common shares outstanding, basic (in shares)	16,955,758	16,998,125
Total dilutive effect of potential common shares (in shares)	91,880	74,049
Weighted average common shares outstanding, diluted (in shares)	17,047,638	17,072,174
Basic earnings per common share (in dollars per share)	$ 0.52	$ 0.36
Diluted earnings per common share (in dollars per share)	$ 0.52	$ 0.36
Antidilutive potential common shares (in shares)	69,748	53,022
Employee Stock Option [Member]
Dilutive effect of potential common shares (in shares)	54,305	53,067
Antidilutive potential common shares (in shares)	64,081	49,743
Restricted Stock [Member]
Dilutive effect of potential common shares (in shares)	37,575	20,982
Antidilutive potential common shares (in shares)	5,667	3,279

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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