EARNINGS PER SHARE (Earnings Per Share Computations) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Basic earnings per common share:
Net income	$ 13,522	$ 13,480	$ 12,803	$ 12,279	$ 12,286	$ 11,565	$ 11,380	$ 11,136	$ 52,084	$ 46,367	$ 43,805
Weighted-average common shares outstanding									25,056,095	24,926,354	24,803,295
Basic earnings per common share	$ 0.54	$ 0.54	$ 0.51	$ 0.49	$ 0.49	$ 0.46	$ 0.46	$ 0.45	$ 2.08	$ 1.86	$ 1.77
Diluted earnings per common share:
Net income	$ 13,522	$ 13,480	$ 12,803	$ 12,279	$ 12,286	$ 11,565	$ 11,380	$ 11,136	$ 52,084	$ 46,367	$ 43,805
Weighted-average common shares outstanding for basic earnings per common share									25,056,095	24,926,354	24,803,295
Add: Dilutive effect of assumed exercise of warrant									184,205	156,563	138,821
Add: Dilutive effect of assumed exercises of stock options and awards									220,427	162,652	230,067
Average shares and dilutive potential common shares									25,460,727	25,245,569	25,172,183
Diluted earnings per common share	$ 0.53	$ 0.53	$ 0.5	$ 0.48	$ 0.49	$ 0.46	$ 0.45	$ 0.44	$ 2.05	$ 1.84	$ 1.74