INVESTMENT SECURITIES - Summary of Amortized Cost and Fair Value (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Securities available-for-sale:
Amortized Cost	$ 2,440,944	$ 2,567,393
Gross Unrealized Gains	11,254	23,679
Gross Unrealized Losses	(27,605)	(15,603)
Fair Value	2,424,593	2,575,469
SBA loan pool securities
Securities available-for-sale:
Amortized Cost	982	1,056
Gross Unrealized Gains	0	2
Gross Unrealized Losses	(12)	0
Fair Value	970	1,058
U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities
Securities available-for-sale:
Amortized Cost	493,757	492,255
Gross Unrealized Gains	7	10
Gross Unrealized Losses	(26,265)	(15,336)
Fair Value	467,499	476,929
Non-agency residential mortgage-backed securities
Securities available-for-sale:
Amortized Cost	651	741
Gross Unrealized Gains	14	16
Gross Unrealized Losses	(1)	(1)
Fair Value	664	756
Non-agency commercial mortgage-backed securities
Securities available-for-sale:
Amortized Cost	201,613	305,172
Gross Unrealized Gains	334	5,339
Gross Unrealized Losses	(1,226)	0
Fair Value	200,721	310,511
Collateralized loan obligations
Securities available-for-sale:
Amortized Cost	1,743,941	1,691,455
Gross Unrealized Gains	10,899	11,129
Gross Unrealized Losses	(101)	(266)
Fair Value	$ 1,754,739	1,702,318
Corporate debt securities
Securities available-for-sale:
Amortized Cost		76,714
Gross Unrealized Gains		7,183
Gross Unrealized Losses		0
Fair Value		$ 83,897

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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-Publisher FASB
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