EARNINGS PER SHARE (Earnings Per Share Computations) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic earnings per common share:
Net income	$ 21,363	$ 20,570	$ 20,142	$ 18,336	$ 11,627	$ 15,825	$ 15,364	$ 14,514	$ 80,411	$ 57,330	$ 52,084
Weighted-average common shares outstanding									25,288,533	25,181,208	25,056,095
Basic earnings per common share	$ 0.84	$ 0.81	$ 0.80	$ 0.73	$ 0.46	$ 0.63	$ 0.61	$ 0.58	$ 3.18	$ 2.28	$ 2.08
Diluted earnings per common share:
Net income	$ 21,363	$ 20,570	$ 20,142	$ 18,336	$ 11,627	$ 15,825	$ 15,364	$ 14,514	$ 80,411	$ 57,330	$ 52,084
Weighted-average common shares outstanding for basic earnings per common share									25,288,533	25,181,208	25,056,095
Add: Dilutive effect of assumed exercise of warrant									225,831	219,273	184,205
Add: Dilutive effect of assumed exercises of stock options and awards									213,467	262,900	220,427
Average shares and dilutive potential common shares									25,727,831	25,663,381	25,460,727
Diluted earnings per common share	$ 0.83	$ 0.80	$ 0.78	$ 0.71	$ 0.45	$ 0.62	$ 0.60	$ 0.57	$ 3.13	$ 2.23	$ 2.05