SECURITIES AVAILABLE FOR SALE, HELD TO MATURITY, AND OTHER - Summary of Securities with Unrealized Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, less than twelve months, gross unrealized losses	$ 19,828	$ 7,960
Available for sale securities, over twelve months, gross unrealized losses	9,312	5,484
Available for sale securities, continuous unrealized loss position, accumulated loss	29,140	13,444
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available for sale securities, continuous unrealized loss position, less than twelve months, fair value	966,619	770,082
Available for sale securities, continuous unrealized loss position, over twelve months, fair value	198,441	211,750
Available for sale securities, continuous unrealized loss position, fair value	1,165,060	981,832
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, accumulated loss	4,426	1,170
Held-to-maturity securities, continuous unrealized loss position, over twelve months, gross unrealized losses	1,660	973
Held to maturity securities, accumulated unrecognized holding loss	6,086	2,143
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Held to maturity securities, accumulated unrecognized holding loss, less than twelve months, fair value	160,409	17,518
Held to maturity securities, accumulated unrecognized holding loss, over twelve months, fair value	31,585	32,946
Held to maturity securities, accumulated unrecognized holding loss, fair value	191,994	50,464
Securities available for sale and held to maturity
Held to maturity and available for sale securities continuous unrealized loss position, less than twelve months, aggregate losses	24,254	9,130
Held to maturity and available for sale securities continuous unrealized loss position, less than twelve months, fair value	1,127,028	787,600
Held to maturity and available for sale securities continuous unrealized loss position, over twelve months, aggregate losses	10,972	6,457
Held to maturity and available for sale securities continuous unrealized loss position, over twelve months, fair value	230,026	244,696
Held to maturity and available for sale securities continuous unrealized loss position, aggregate losses	35,226	15,587
Held to maturity and available for sale securities continuous unrealized loss position, fair value	1,357,054	1,032,296
Debt securities \| Municipal bonds and obligations
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, less than twelve months, gross unrealized losses	128	0
Available for sale securities, over twelve months, gross unrealized losses	593	206
Available for sale securities, continuous unrealized loss position, accumulated loss	721	206
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available for sale securities, continuous unrealized loss position, less than twelve months, fair value	4,399	0
Available for sale securities, continuous unrealized loss position, over twelve months, fair value	8,582	8,985
Available for sale securities, continuous unrealized loss position, fair value	12,981	8,985
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, accumulated loss	2,779	35
Held-to-maturity securities, continuous unrealized loss position, over twelve months, gross unrealized losses	201	55
Held to maturity securities, accumulated unrecognized holding loss	2,980	90
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Held to maturity securities, accumulated unrecognized holding loss, less than twelve months, fair value	112,585	10,213
Held to maturity securities, accumulated unrecognized holding loss, over twelve months, fair value	1,915	2,059
Held to maturity securities, accumulated unrecognized holding loss, fair value	114,500	12,272
Debt securities \| Agency collateralized mortgage obligations
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, less than twelve months, gross unrealized losses	16,667	6,849
Available for sale securities, over twelve months, gross unrealized losses	3,149	2,095
Available for sale securities, continuous unrealized loss position, accumulated loss	19,816	8,944
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available for sale securities, continuous unrealized loss position, less than twelve months, fair value	816,169	655,479
Available for sale securities, continuous unrealized loss position, over twelve months, fair value	78,858	80,401
Available for sale securities, continuous unrealized loss position, fair value	895,027	735,880
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, accumulated loss	444	0
Held-to-maturity securities, continuous unrealized loss position, over twelve months, gross unrealized losses	634	486
Held to maturity securities, accumulated unrecognized holding loss	1,078	486
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Held to maturity securities, accumulated unrecognized holding loss, less than twelve months, fair value	32,112	0
Held to maturity securities, accumulated unrecognized holding loss, over twelve months, fair value	12,317	12,946
Held to maturity securities, accumulated unrecognized holding loss, fair value	44,429	12,946
Debt securities \| Agency mortgage-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, less than twelve months, gross unrealized losses	2,715	765
Available for sale securities, over twelve months, gross unrealized losses	2,808	1,500
Available for sale securities, continuous unrealized loss position, accumulated loss	5,523	2,265
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available for sale securities, continuous unrealized loss position, less than twelve months, fair value	123,776	95,800
Available for sale securities, continuous unrealized loss position, over twelve months, fair value	62,093	65,323
Available for sale securities, continuous unrealized loss position, fair value	185,869	161,123
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, accumulated loss	0	0
Held-to-maturity securities, continuous unrealized loss position, over twelve months, gross unrealized losses	316	164
Held to maturity securities, accumulated unrecognized holding loss	316	164
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Held to maturity securities, accumulated unrecognized holding loss, less than twelve months, fair value	0	0
Held to maturity securities, accumulated unrecognized holding loss, over twelve months, fair value	7,397	7,728
Held to maturity securities, accumulated unrecognized holding loss, fair value	7,397	7,728
Debt securities \| Agency commercial mortgage-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, less than twelve months, gross unrealized losses	268	334
Available for sale securities, over twelve months, gross unrealized losses	2,735	1,427
Available for sale securities, continuous unrealized loss position, accumulated loss	3,003	1,761
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available for sale securities, continuous unrealized loss position, less than twelve months, fair value	13,647	17,379
Available for sale securities, continuous unrealized loss position, over twelve months, fair value	46,911	39,268
Available for sale securities, continuous unrealized loss position, fair value	60,558	56,647
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, accumulated loss	0	0
Held-to-maturity securities, continuous unrealized loss position, over twelve months, gross unrealized losses	509	268
Held to maturity securities, accumulated unrecognized holding loss	509	268
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Held to maturity securities, accumulated unrecognized holding loss, less than twelve months, fair value	0	0
Held to maturity securities, accumulated unrecognized holding loss, over twelve months, fair value	9,956	10,213
Held to maturity securities, accumulated unrecognized holding loss, fair value	9,956	10,213
Debt securities \| Corporate bonds
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, less than twelve months, gross unrealized losses	32	1
Available for sale securities, over twelve months, gross unrealized losses	0	236
Available for sale securities, continuous unrealized loss position, accumulated loss	32	237
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available for sale securities, continuous unrealized loss position, less than twelve months, fair value	7,544	328
Available for sale securities, continuous unrealized loss position, over twelve months, fair value	0	15,769
Available for sale securities, continuous unrealized loss position, fair value	7,544	16,097
Debt securities \| Trust preferred securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, less than twelve months, gross unrealized losses		0
Available for sale securities, over twelve months, gross unrealized losses		0
Available for sale securities, continuous unrealized loss position, accumulated loss		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available for sale securities, continuous unrealized loss position, less than twelve months, fair value		0
Available for sale securities, continuous unrealized loss position, over twelve months, fair value		0
Available for sale securities, continuous unrealized loss position, fair value		0
Debt securities \| Other bonds and obligations
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, less than twelve months, gross unrealized losses	18	11
Available for sale securities, over twelve months, gross unrealized losses	27	20
Available for sale securities, continuous unrealized loss position, accumulated loss	45	31
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available for sale securities, continuous unrealized loss position, less than twelve months, fair value	1,084	1,096
Available for sale securities, continuous unrealized loss position, over twelve months, fair value	1,997	2,004
Available for sale securities, continuous unrealized loss position, fair value	3,081	3,100
Debt securities \| Tax advantaged economic development bonds
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, accumulated loss	1,203	1,135
Held-to-maturity securities, continuous unrealized loss position, over twelve months, gross unrealized losses	0	0
Held to maturity securities, accumulated unrecognized holding loss	1,203	1,135
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Held to maturity securities, accumulated unrecognized holding loss, less than twelve months, fair value	15,712	7,305
Held to maturity securities, accumulated unrecognized holding loss, over twelve months, fair value	0	0
Held to maturity securities, accumulated unrecognized holding loss, fair value	$ 15,712	$ 7,305

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Represents the excess of amortized cost basis over the fair value of securities that have been in a loss position for twelve months or longer for those securities that are categorized as held-to-maturity and available-for-sale.

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Represents the excess of amortized cost basis over the fair value of securities that have been in a loss position, which are categorized as held-to-maturity and available-for-sale.

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Represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized as held-to-maturity and available-for-sale securities.

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Represents the excess of amortized cost basis over the fair value of securities that have been in a loss position for less than twelve months for those securities that are categorized as held-to-maturity and available-for-sale.

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Represents the aggregate fair value of investments in debt and equity securities categorized as held-to-maturity and available-for-sale that have been in a continuous unrealized loss position for less than twelve months.

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.

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