SECURITIES (Schedule of Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Securities [Line Items]
Securities—trading, Amortized Cost	$ 27,203	$ 27,203
Securities—trading	25,838	25,896
Available-for-sale Securities, Amortized Cost	1,599,347	1,648,421
Available-for-sale Securities, Gross Unrealized Gains	14,383	7,171
Available-for-sale Securities, Gross Unrealized Losses	(9,926)	(19,369)
Securities—available-for-sale	1,603,804	1,636,223
Held-to-maturity Securities, Amortized Cost	218,993	234,220
Held-to-maturity Securities, Gross Unrealized Gains	2,681	1,807
Held-to-maturity Securities, Gross Unrealized Losses	1,562	3,490
Securities—held-to-maturity	220,112	232,537
U.S. Government and agency obligations [Member]
Schedule of Securities [Line Items]
Available-for-sale Securities, Amortized Cost	139,621	151,012
Available-for-sale Securities, Gross Unrealized Gains	134	149
Available-for-sale Securities, Gross Unrealized Losses	(1,440)	(2,049)
Securities—available-for-sale	138,315	149,112
Held-to-maturity Securities, Amortized Cost	389	1,006
Held-to-maturity Securities, Gross Unrealized Gains	3	14
Held-to-maturity Securities, Gross Unrealized Losses	0	1
Securities—held-to-maturity	392	1,019
Municipal bonds [Member]
Schedule of Securities [Line Items]
Available-for-sale Securities, Amortized Cost	116,954	116,548
Available-for-sale Securities, Gross Unrealized Gains	3,288	1,806
Available-for-sale Securities, Gross Unrealized Losses	(187)	(532)
Securities—available-for-sale	120,055	117,822
Held-to-maturity Securities, Amortized Cost	163,614	176,663
Held-to-maturity Securities, Gross Unrealized Gains	2,527	1,727
Held-to-maturity Securities, Gross Unrealized Losses	1,248	2,578
Securities—held-to-maturity	164,893	175,812
Corporate bonds [Member]
Schedule of Securities [Line Items]
Securities—trading, Amortized Cost	27,203	27,203
Securities—trading	25,838	25,896
Available-for-sale Securities, Amortized Cost	4,057	3,556
Available-for-sale Securities, Gross Unrealized Gains	4	0
Available-for-sale Securities, Gross Unrealized Losses	(17)	(61)
Securities—available-for-sale	4,044	3,495
Held-to-maturity Securities, Amortized Cost	3,701	3,736
Held-to-maturity Securities, Gross Unrealized Gains	0	0
Held-to-maturity Securities, Gross Unrealized Losses	13	13
Securities—held-to-maturity	3,688	3,723
Mortgage-backed or related securities [Member]
Schedule of Securities [Line Items]
Available-for-sale Securities, Amortized Cost	1,320,826	1,355,258
Available-for-sale Securities, Gross Unrealized Gains	10,952	5,210
Available-for-sale Securities, Gross Unrealized Losses	(8,201)	(16,607)
Securities—available-for-sale	1,323,577	1,343,861
Held-to-maturity Securities, Amortized Cost	51,289	52,815
Held-to-maturity Securities, Gross Unrealized Gains	151	66
Held-to-maturity Securities, Gross Unrealized Losses	301	898
Securities—held-to-maturity	51,139	51,983
Asset-backed Securities [Member]
Schedule of Securities [Line Items]
Available-for-sale Securities, Amortized Cost	17,889	22,047
Available-for-sale Securities, Gross Unrealized Gains	5	6
Available-for-sale Securities, Gross Unrealized Losses	(81)	(120)
Securities—available-for-sale	$ 17,813	$ 21,933

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

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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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-Publisher FASB
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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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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Amount, before other-than-temporary impairment (OTTI) accretion, of investment in debt securities measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Cost of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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