INCOME TAXES - Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Taxes calculated at statutory rate	$ 21,385	$ (481)	$ 9,014
Increase (decrease) resulting from:
State tax expense, net of federal effect	195	386	196
Non-deductible expenses	51	51	45
Non-deductible dues	37	35	31
Bank-owned life insurance income	(321)	(326)	(141)
Incentive stock option compensation expense	(187)	(16)	0
Tax exempt interest income	(34)	(17)	0
Non-deductible M&A and acquisition related costs	0	0	857
Other, net	0	(34)	312
Change in applicable statutory rate	5,838	0	0
Total income tax provision	$ 26,964	$ (402)	$ 10,314