INVESTMENT SECURITIES - Contractual Maturity Schedule (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Amortized Cost
Within one year	$ 0
One to five years	15,000
Five to ten years	224,884
Greater than ten years	0
Collateralized loan obligations, SBA loan pool, private label residential mortgage-backed, commercial mortgage-backed, and agency mortgage-backed securities	722,431
Amortized Cost	962,315	$ 962,203
Fair Value
Within one year	0
One to five years	15,075
Five to ten years	240,924
Greater than ten years	0
Collateralized loan obligations, SBA loan pool, private label residential mortgage-backed, commercial mortgage-backed, and agency mortgage-backed securities	740,320
Total	996,319	932,285
Amortized Cost
Within one year	0
One to five years	43,500
Five to ten years	28,822
Greater than ten years	0
Collateralized loan obligations, SBA loan pool, private label residential mortgage-backed, commercial mortgage-backed, and agency mortgage-backed securities	1,857,185
Amortized Cost	1,929,507	838,768
Fair Value
Within one year	0
One to five years	44,504
Five to ten years	29,093
Greater than ten years	0
Collateralized loan obligations, SBA loan pool, private label residential mortgage-backed, commercial mortgage-backed, and agency mortgage-backed securities	1,867,991
Total	$ 1,941,588	$ 833,596