INVESTMENT SECURITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 143,971	$ 0
Held-to-maturity investment security, at fair value	144,593
Schedule of Available-for-sale Securities
Amortized Cost	3,385,441	3,783,829
Gross Unrealized Gains	6,695	11,744
Gross Unrealized Losses	(56,341)	(22,347)
Available-for-sale investment securities, fair value	3,335,795	3,773,226
Marketable Securities [Abstract]
Amortized Cost	3,529,412
Gross Unrealized Gains	7,317
Gross Unrealized Losses	(56,341)
Marketable securities, at fair Value	3,480,388
U.S. Treasury securities
Schedule of Available-for-sale Securities
Amortized Cost	730,287	1,002,874
Gross Unrealized Gains	21	33
Gross Unrealized Losses	(9,829)	(4,392)
Available-for-sale investment securities, fair value	720,479	998,515
U.S. government agency and U.S. government sponsored enterprise debt securities
Schedule of Available-for-sale Securities
Amortized Cost	277,891	771,288
Gross Unrealized Gains	224	555
Gross Unrealized Losses	(3,249)	(2,994)
Available-for-sale investment securities, fair value	274,866	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	272,672	354,418
Gross Unrealized Gains	345	268
Gross Unrealized Losses	(6,218)	(3,024)
Available-for-sale investment securities, fair value	266,799	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	1,266,372	996,255
Gross Unrealized Gains	3,924	7,542
Gross Unrealized Losses	(11,549)	(6,401)
Available-for-sale investment securities, fair value	1,258,747	997,396
Municipal securities
Schedule of Available-for-sale Securities
Amortized Cost	148,302	173,785
Gross Unrealized Gains	1,252	2,657
Gross Unrealized Losses	(1,900)	(793)
Available-for-sale investment securities, fair value	147,654	175,649
Non-agency residential mortgage-backed securities \| Investment grade
Schedule of Available-for-sale Securities
Amortized Cost	11,592	62,133
Gross Unrealized Gains	0	433
Gross Unrealized Losses	(115)	(173)
Available-for-sale investment securities, fair value	11,477	62,393
Corporate debt securities \| Investment grade
Schedule of Available-for-sale Securities
Amortized Cost	222,190	280,850
Gross Unrealized Gains	562	129
Gross Unrealized Losses	(375)	(1,547)
Available-for-sale investment securities, fair value	222,377	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	(1,018)	(1,849)
Available-for-sale investment securities, fair value	9,173	9,642
Foreign bonds \| Investment grade
Schedule of Available-for-sale Securities
Amortized Cost	405,443	90,586
Gross Unrealized Gains	30	3
Gross Unrealized Losses	(21,579)	(794)
Available-for-sale investment securities, fair value	383,894	89,795
Foreign bonds \| Investment grade \| Multilateral development bank
Schedule of Available-for-sale Securities
Available-for-sale investment securities, fair value	353,600	49,700
Other securities
Schedule of Available-for-sale Securities
Amortized Cost	40,501	40,149
Gross Unrealized Gains	337	124
Gross Unrealized Losses	(509)	(380)
Available-for-sale investment securities, fair value	40,329	$ 39,893
Non-agency commercial mortgage-backed security
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	143,971
Gross Unrealized Gains	622
Gross Unrealized Losses	0
Held-to-maturity investment security, at fair value	$ 144,593

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