INVESTMENT SECURITIES - Contractual Maturity Schedule (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Amortized Cost
Within one year	$ 0
One to five years	15,000
Five to ten years	225,304
Greater than ten years	0
Collateralized loan obligations, SBA loan pool, private label residential mortgage-backed, commercial mortgage-backed, and agency mortgage-backed securities	622,965
Amortized Cost	863,269	$ 884,234
Fair Value
Within one year	0
One to five years	15,131
Five to ten years	238,895
Greater than ten years	0
Collateralized loan obligations, SBA loan pool, private label residential mortgage-backed, commercial mortgage-backed, and agency mortgage-backed securities	625,872
Total	879,898	899,743
Amortized Cost
Within one year	0
One to five years	10,000
Five to ten years	9,134
Greater than ten years	0
Collateralized loan obligations, SBA loan pool, private label residential mortgage-backed, commercial mortgage-backed, and agency mortgage-backed securities	2,432,017
Amortized Cost	2,451,151	2,396,968
Fair Value
Within one year	0
One to five years	10,087
Five to ten years	9,057
Greater than ten years	0
Collateralized loan obligations, SBA loan pool, private label residential mortgage-backed, commercial mortgage-backed, and agency mortgage-backed securities	2,415,397
Total	$ 2,434,541	$ 2,381,488