INVESTMENTS - Summary of Held-To-Maturity and Available-For-Sale Investment Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Investment Holdings [Line Items]
Total	$ 696,269	$ 763,254
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	7,202	6,236
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(4,749)	(5,915)
Held-to-Maturity Market Value	698,722	763,575
Total	1,295,377	1,045,337
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	8,941	4,716
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(5,740)	(10,183)
Investment securities available-for-sale	1,298,578	1,039,870
U.S. Treasuries
Investment Holdings [Line Items]
Total	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0	0
Held-to-Maturity Market Value	0	0
Total	98	98
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	0	0
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	0	(1)
Investment securities available-for-sale	98	97
Securities of U.S. government agencies and corporations
Investment Holdings [Line Items]
Total	12,130	13,011
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	28	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(17)	(110)
Held-to-Maturity Market Value	12,141	12,901
Total	16,967	7,056
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	159	0
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	0	(40)
Investment securities available-for-sale	17,126	7,016
Residential Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Total	181,553	205,522
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	1,996	1,740
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(1,338)	(1,166)
Held-to-Maturity Market Value	182,211	206,096
Total	262,052	184,960
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	1,140	1,175
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(2,019)	(2,740)
Investment securities available-for-sale	261,173	183,395
Commercial Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Total	261,739	278,728
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	3,156	3,254
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(1,912)	(1,817)
Held-to-Maturity Market Value	262,983	280,165
Total	157,138	154,239
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	682	188
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(412)	(826)
Investment securities available-for-sale	157,408	153,601
Collateralized Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Total	165,625	195,408
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	1,138	1,125
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(1,083)	(1,476)
Held-to-Maturity Market Value	165,680	195,057
Total	324,712	232,701
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	1,289	634
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(1,609)	(2,321)
Investment securities available-for-sale	324,392	231,014
Obligations of state and other political subdivisions
Investment Holdings [Line Items]
Total	75,222	70,585
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	884	117
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(399)	(1,346)
Held-to-Maturity Market Value	75,707	69,356
Total	122,511	96,934
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	2,206	1,461
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(889)	(1,514)
Investment securities available-for-sale	123,828	96,881
Asset-backed Securities [Member]
Investment Holdings [Line Items]
Total	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0	0
Held-to-Maturity Market Value	0	0
Total	327,564	322,708
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	1,717	517
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(504)	(2,013)
Investment securities available-for-sale	328,777	321,212
Other securities
Investment Holdings [Line Items]
Total	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0	0
Held-to-Maturity Market Value	0	0
Total	84,335	46,641
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	1,748	741
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(307)	(728)
Investment securities available-for-sale	$ 85,776	$ 46,654

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

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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