SECURITIES AVAILABLE FOR SALE - Summary of Securities Available for Sale (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Amortized Cost	$ 726,677	$ 719,983
Gross Unrealized Gains	2,075	5,036
Gross Unrealized Losses	18,605	7,777
Fair Value	710,147	717,242
Obligations of US Government-sponsored enterprises
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Amortized Cost	3,991	6,967
Gross Unrealized Gains	0	5
Gross Unrealized Losses	3	0
Fair Value	3,988	6,972
US Government-sponsored enterprises
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Amortized Cost	459,957	447,081
Gross Unrealized Gains	521	1,738
Gross Unrealized Losses	13,628	5,816
Fair Value	446,850	443,003
US Government agency
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Amortized Cost	88,545	96,357
Gross Unrealized Gains	195	413
Gross Unrealized Losses	2,486	1,174
Fair Value	86,254	95,596
Private label
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Amortized Cost	446	529
Gross Unrealized Gains	124	150
Gross Unrealized Losses	6	5
Fair Value	564	674
Obligations of states and political subdivisions thereof
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Amortized Cost	135,374	138,522
Gross Unrealized Gains	1,053	2,407
Gross Unrealized Losses	2,041	729
Fair Value	134,386	140,200
Corporate bonds
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Amortized Cost	38,364	30,527
Gross Unrealized Gains	182	323
Gross Unrealized Losses	441	53
Fair Value	$ 38,105	$ 30,797

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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