DERIVATIVE FINANCIAL INSTRUMENTS - Notional Amounts and Estimated Fair Values of the Non-hedging Derivatives (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivative disclosures
Estimated Fair Value, Asset Derivative	$ 2,876	$ 1,824
Estimated Fair Value, Liability Derivative	2,941	1,848
Offsetting derivatives assets/liabilities, Asset Derivative	(240)	(369)
Offsetting derivatives assets/liabilities, Liability Derivative	(240)	(369)
Net derivatives included in the consolidated balance sheets, Asset Derivative	2,636	1,455
Net derivatives included in the consolidated balance sheets, Liability Derivative	2,701	1,479
Interest rate swaps | Correspondent
Derivative disclosures
Notional Amount	188,408	173,304
Estimated Fair Value, Asset Derivative	2,309	1,326
Estimated Fair Value, Liability Derivative	493	448
Interest rate swaps | Customer
Derivative disclosures
Notional Amount	188,408	173,304
Estimated Fair Value, Asset Derivative	417	423
Estimated Fair Value, Liability Derivative	2,298	1,325
Interest rate caps and collars | Correspondent
Derivative disclosures
Notional Amount	37,248	37,466
Estimated Fair Value, Asset Derivative	150	75
Interest rate caps and collars | Customer
Derivative disclosures
Notional Amount	37,248	37,466
Estimated Fair Value, Liability Derivative	$ 150	$ 75