EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
SHARE-BASED COMPENSATION
Net income	$ 11,466	$ 12,206	$ 34,784	$ 34,936
Weighted average shares outstanding - basic	30,943,756	31,330,964	31,088,729	32,548,479
Weighted average shares outstanding - diluted	31,142,128	31,749,880	31,277,402	32,932,347
Basic earnings per common share (in dollars per share)	$ 0.37	$ 0.39	$ 1.12	$ 1.07
Diluted earnings per common share (in dollars per share)	$ 0.37	$ 0.38	$ 1.11	$ 1.06
Antidilutive securities excluded from the dilutive share calculation (in shares)	8,902	12,532	9,381	12,996
Stock Option
SHARE-BASED COMPENSATION
Dilutive effect of share-based compensation arrangements	198,372	418,916	188,673	383,868

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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