INVESTMENT SECURITIES - Summary of Amortized Cost and Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Held-to-maturity
Amortized Cost	$ 884,234	$ 962,203
Gross Unrealized Gains	17,442	296
Gross Unrealized Losses	(1,933)	(30,214)
Securities held-to-maturity	899,743	932,285
Available-for-sale
Amortized Cost	2,396,968	838,768
Gross Unrealized Gains	12,958	198
Gross Unrealized Losses	(28,438)	(5,370)
Fair Value	2,381,488	833,596
SBA loan pool securities
Available-for-sale
Amortized Cost	1,221	1,485
Gross Unrealized Gains	0	19
Gross Unrealized Losses	0	0
Fair Value	1,221	1,504
Private label residential mortgage-backed securities
Available-for-sale
Amortized Cost	121,397	1,755
Gross Unrealized Gains	18	14
Gross Unrealized Losses	(4,238)	(1)
Fair Value	117,177	1,768
Corporate bonds
Available-for-sale
Amortized Cost	48,574	26,657
Gross Unrealized Gains	482	0
Gross Unrealized Losses	(108)	(505)
Fair Value	48,948	26,152
Collateralized loan obligations
Available-for-sale
Amortized Cost	1,395,094	111,719
Gross Unrealized Gains	12,449	31
Gross Unrealized Losses	(674)	(282)
Fair Value	1,406,869	111,468
Agency mortgage-backed securities
Available-for-sale
Amortized Cost	830,682	697,152
Gross Unrealized Gains	9	134
Gross Unrealized Losses	(23,418)	(4,582)
Fair Value	807,273	692,704
Corporate bonds
Held-to-maturity
Amortized Cost	240,090	239,274
Gross Unrealized Gains	13,032	255
Gross Unrealized Losses	(91)	(20,946)
Securities held-to-maturity	253,031	218,583
Collateralized loan obligations
Held-to-maturity
Amortized Cost	338,226	416,284
Gross Unrealized Gains	1,461	0
Gross Unrealized Losses	(61)	(5,077)
Securities held-to-maturity	339,626	411,207
Commercial mortgage-backed securities
Held-to-maturity
Amortized Cost	305,918	306,645
Gross Unrealized Gains	2,949	41
Gross Unrealized Losses	(1,781)	(4,191)
Securities held-to-maturity	$ 307,086	$ 302,495

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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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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