EARNINGS PER SHARE (Computation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 14,057	$ 11,339	$ 39,094	$ 31,649
Dividends and undistributed earnings allocated to participating securities	(39)	(46)	(110)	(134)
Net income available to common shareholders	$ 14,018	$ 11,293	$ 38,984	$ 31,515
Weighted-average common shares outstanding for basic EPS	15,580,782	15,515,189	15,565,355	15,505,698
Dilutive effect of stock-based awards (shares)	58,204	73,819	56,045	74,374
Weighted-average common and potential common shares for diluted EPS (shares)	15,638,986	15,589,008	15,621,400	15,580,072
Basic EPS (in dollars per share)	$ 0.90	$ 0.72	$ 2.50	$ 2.03
Diluted EPS (in dollars per share)	$ 0.90	$ 0.72	$ 2.50	$ 2.02
Antidilutive Stock options (shares)	0	0	0	0