EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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 and Diluted Earnings:
Net Income	$ 17,381	$ 20,303	$ 20,203	$ 16,251	$ 10,331	$ 14,511	$ 14,481	$ 14,989	$ 74,138	$ 54,312	$ 49,349
Basic weighted-average shares outstanding (in shares)									34,951	29,841	27,118
Add: Stock options (in shares)									165	206	129
Diluted weighted-average shares outstanding (in shares)									35,116	30,047	27,247
Basic Earnings Per Share:
Earnings per common share - basic (in dollars per share)	$ 0.50	$ 0.58	$ 0.58	$ 0.46	$ 0.33	$ 0.49	$ 0.49	$ 0.51	$ 2.12	$ 1.82	$ 1.82
Diluted Earnings Per Share:
Earnings per common share - diluted (in dollars per share)	$ 0.50	$ 0.58	$ 0.57	$ 0.46	$ 0.33	$ 0.49	$ 0.49	$ 0.51	$ 2.11	$ 1.81	$ 1.81
Antidilutive securities from non-qualified stock options excluded from calculating earnings
Number of antidilutive options (in shares)									356	154	359