INVESTMENT SECURITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities
Amortized Cost	$ 3,224,807	$ 3,783,829
Gross Unrealized Gains	21,463	11,744
Gross Unrealized Losses	(9,646)	(22,347)
Available-for-sale investment securities, at fair value	3,236,624	3,773,226
Schedule of Held-to-maturity Security
Amortized Cost	154,461	0
Fair Value	154,296
Investment Securities
Amortized Cost	3,379,268
Gross Unrealized Gains	21,463
Gross Unrealized Losses	(9,811)
Fair Value	3,390,920
U.S. Treasury securities
Schedule of Available-for-sale Securities
Amortized Cost	455,019	1,002,874
Gross Unrealized Gains	1,440	33
Gross Unrealized Losses	(11)	(4,392)
Available-for-sale investment securities, at fair value	456,448	998,515
U.S. government agency and U.S. government sponsored enterprise debt securities
Schedule of Available-for-sale Securities
Amortized Cost	381,986	771,288
Gross Unrealized Gains	1,386	555
Gross Unrealized Losses	(41)	(2,994)
Available-for-sale investment securities, at fair value	383,331	768,849
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Schedule of Available-for-sale Securities
Amortized Cost	325,486	354,418
Gross Unrealized Gains	2,791	268
Gross Unrealized Losses	(1,459)	(3,024)
Available-for-sale investment securities, at fair value	326,818	351,662
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Schedule of Available-for-sale Securities
Amortized Cost	1,188,753	996,255
Gross Unrealized Gains	8,538	7,542
Gross Unrealized Losses	(2,453)	(6,401)
Available-for-sale investment securities, at fair value	1,194,838	997,396
Municipal securities
Schedule of Available-for-sale Securities
Amortized Cost	149,008	173,785
Gross Unrealized Gains	3,423	2,657
Gross Unrealized Losses	(138)	(793)
Available-for-sale investment securities, at fair value	152,293	175,649
Non-agency residential mortgage-backed securities \| Investment grade
Schedule of Available-for-sale Securities
Amortized Cost	51,396	62,133
Gross Unrealized Gains	1,578	433
Gross Unrealized Losses	(17)	(173)
Available-for-sale investment securities, at fair value	52,957	62,393
Corporate debt securities \| Investment grade
Schedule of Available-for-sale Securities
Amortized Cost	282,106	280,850
Gross Unrealized Gains	533	129
Gross Unrealized Losses	(652)	(1,547)
Available-for-sale investment securities, at fair value	281,987	279,432
Corporate debt securities \| Non-investment grade
Schedule of Available-for-sale Securities
Amortized Cost	10,191	11,491
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1,413)	(1,849)
Available-for-sale investment securities, at fair value	8,778	9,642
Foreign bonds \| Investment grade
Schedule of Available-for-sale Securities
Amortized Cost	340,474	90,586
Gross Unrealized Gains	419	3
Gross Unrealized Losses	(3,459)	(794)
Available-for-sale investment securities, at fair value	337,434	89,795
Foreign bonds \| Multilateral development bank \| Investment grade
Schedule of Available-for-sale Securities
Available-for-sale investment securities, at fair value	296,800	49,700
Other securities
Schedule of Available-for-sale Securities
Amortized Cost	40,388	40,149
Gross Unrealized Gains	1,355	124
Gross Unrealized Losses	(3)	(380)
Available-for-sale investment securities, at fair value	41,740	$ 39,893
Non-agency commercial mortgage-backed security
Schedule of Held-to-maturity Security
Amortized Cost	154,461
Gross Unrealized Gains	0
Gross Unrealized Losses	(165)
Fair Value	$ 154,296

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