MARKETABLE SECURITIES - Schedule of Amortized Cost and Fair Value of Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Available for sale:
Amortized Cost	$ 241,909	$ 235,849
Gross Unrealized Gains	0	69
Gross Unrealized Losses	9,531	3,546
Estimated Fair Value	232,378	232,372
Held to maturity:
Amortized Cost	164,839	174,684
Gross Unrealized Gains	833	2,554
Gross Unrealized Losses	3,076	448
Estimated Fair Value	162,596	176,790
Corporate bonds
Available for sale:
Amortized Cost	19,762	18,823
Gross Unrealized Gains	0	64
Gross Unrealized Losses	648	50
Estimated Fair Value	19,114	18,837
Municipal securities
Available for sale:
Amortized Cost	15,814	7,746
Gross Unrealized Gains	0	0
Gross Unrealized Losses	451	200
Estimated Fair Value	15,363	7,546
Held to maturity:
Amortized Cost	142,419	146,496
Gross Unrealized Gains	710	2,244
Gross Unrealized Losses	2,420	218
Estimated Fair Value	140,709	148,522
Mortgage-backed securities
Available for sale:
Amortized Cost	91,208	92,471
Gross Unrealized Gains	0	0
Gross Unrealized Losses	4,447	1,793
Estimated Fair Value	86,761	90,678
Held to maturity:
Amortized Cost	17,871	22,026
Gross Unrealized Gains	77	199
Gross Unrealized Losses	611	230
Estimated Fair Value	17,337	21,995
Collateralized mortgage obligations
Available for sale:
Amortized Cost	115,125	116,809
Gross Unrealized Gains	0	5
Gross Unrealized Losses	3,985	1,503
Estimated Fair Value	111,140	115,311
Held to maturity:
Amortized Cost	4,549	6,162
Gross Unrealized Gains	46	111
Gross Unrealized Losses	45	0
Estimated Fair Value	$ 4,550	$ 6,273

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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