INVESTMENT SECURITIES - Summary of Investment Securities with Unrealized Losses (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value
Less Than 12 Months	$ 80,184	$ 878,890
12 Months or Longer	56,095	0
Total	136,279	878,890
Gross Unrealized Losses
Less Than 12 Months	(1,878)	(30,214)
12 Months or Longer	(55)	0
Total	(1,933)	(30,214)
Fair Value
Less Than 12 Months	1,110,832	698,170
12 Months or Longer	4,520	7,235
Total	1,115,352	705,405
Gross Unrealized Losses
Less Than 12 Months	(28,322)	(5,246)
12 Months or Longer	(116)	(124)
Total	(28,438)	(5,370)
Corporate bonds
Fair Value
Less Than 12 Months	9,907	190,332
12 Months or Longer	0	0
Total	9,907	190,332
Gross Unrealized Losses
Less Than 12 Months	(91)	(20,946)
12 Months or Longer	0	0
Total	(91)	(20,946)
Fair Value
Less Than 12 Months	0	26,152
12 Months or Longer	3,530	0
Total	3,530	26,152
Gross Unrealized Losses
Less Than 12 Months	0	(505)
12 Months or Longer	(108)	0
Total	(108)	(505)
Collateralized loan obligations
Fair Value
Less Than 12 Months	10,056	411,207
12 Months or Longer	56,095	0
Total	66,151	411,207
Gross Unrealized Losses
Less Than 12 Months	(6)	(5,077)
12 Months or Longer	(55)	0
Total	(61)	(5,077)
Fair Value
Less Than 12 Months	187,592	72,204
12 Months or Longer	0	0
Total	187,592	72,204
Gross Unrealized Losses
Less Than 12 Months	(674)	(282)
12 Months or Longer	0	0
Total	(674)	(282)
Commercial mortgage-backed securities
Fair Value
Less Than 12 Months	60,221	277,351
12 Months or Longer	0	0
Total	60,221	277,351
Gross Unrealized Losses
Less Than 12 Months	(1,781)	(4,191)
12 Months or Longer	0	0
Total	(1,781)	(4,191)
SBA loan pool securities
Fair Value
Less Than 12 Months	1,221
12 Months or Longer	0
Total	1,221
Gross Unrealized Losses
Less Than 12 Months	0
12 Months or Longer	0
Total	0
Private label residential mortgage-backed securities
Fair Value
Less Than 12 Months	116,216	0
12 Months or Longer	230	403
Total	116,446	403
Gross Unrealized Losses
Less Than 12 Months	(4,238)	0
12 Months or Longer	0	(1)
Total	(4,238)	(1)
Agency mortgage-backed securities
Fair Value
Less Than 12 Months	805,803	599,814
12 Months or Longer	760	6,832
Total	806,563	606,646
Gross Unrealized Losses
Less Than 12 Months	(23,410)	(4,459)
12 Months or Longer	(8)	(123)
Total	$ (23,418)	$ (4,582)