SECURITIES AVAILABLE FOR SALE - Summary of Securities Available for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Available-for-sale securities, amortized cost basis	$ 732,002	$ 719,983
Gross Unrealized Gains	2,491	5,036
Gross Unrealized Losses	15,934	7,777
Fair Value	718,559	717,242
Obligations of US Government sponsored enterprises
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Available-for-sale securities, amortized cost basis	6,982	6,967
Gross Unrealized Gains	1	5
Gross Unrealized Losses	6	0
Fair Value	6,977	6,972
US Government-sponsored enterprises
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Available-for-sale securities, amortized cost basis	459,601	447,081
Gross Unrealized Gains	838	1,738
Gross Unrealized Losses	11,264	5,816
Fair Value	449,175	443,003
US Government agency
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Available-for-sale securities, amortized cost basis	92,286	96,357
Gross Unrealized Gains	275	413
Gross Unrealized Losses	2,165	1,174
Fair Value	90,396	95,596
Private label
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Available-for-sale securities, amortized cost basis	484	529
Gross Unrealized Gains	137	150
Gross Unrealized Losses	5	5
Fair Value	616	674
Obligations of states and political subdivisions thereof
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Available-for-sale securities, amortized cost basis	136,244	138,522
Gross Unrealized Gains	1,079	2,407
Gross Unrealized Losses	2,046	729
Fair Value	135,277	140,200
Corporate bonds
Available-for-sale Securities, Fair Value to Amortized Cost Basis
Available-for-sale securities, amortized cost basis	36,405	30,527
Gross Unrealized Gains	161	323
Gross Unrealized Losses	448	53
Fair Value	$ 36,118	$ 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
-SubTopic 10
-Section 25
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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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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