EARNINGS PER SHARE (Computation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 12,820	$ 10,076
Dividends and undistributed earnings allocated to participating securities	(40)	(45)
Net income available to common shareholders	$ 12,780	$ 10,031
Weighted-average common shares outstanding for basic EPS	15,541,975	15,488,848
Dilutive effect of stock-based awards (shares)	61,405	79,791
Weighted-average common and potential common shares for diluted EPS (shares)	15,603,380	15,568,639
Basic EPS (in dollars per share)	$ 0.82	$ 0.65
Diluted EPS (in dollars per share)	$ 0.82	$ 0.64
Antidilutive Stock options (shares)	0	0