SECURITIES - Contractual Maturities of Securities Available for Sale (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Available for Sale, Amortized Cost
Within one year	$ 13,756
One through five years	59,616
Six through ten years	119,452
After ten years	150,715
Amortized Cost, Equity securities	4,670
Amortized Cost	994,231	$ 905,857
Available for Sale, Fair Value
Within one year	13,867
One through five years	63,105
Six through ten years	127,933
After ten years	162,729
Equity securities	4,670
Fair Value	1,032,380	925,279
Mortgage-backed securities-residential (Government Sponsored Entity)
Available for Sale, Amortized Cost
Debt securities without single maturity date	440,766
Amortized Cost	440,766	332,525
Available for Sale, Fair Value
Debt securities without single maturity date	450,362
Fair Value	450,362	334,080
Collateralized mortgage obligations (Government Sponsored Entity)
Available for Sale, Amortized Cost
Debt securities without single maturity date	205,256
Amortized Cost	205,256	228,621
Available for Sale, Fair Value
Debt securities without single maturity date	209,714
Fair Value	$ 209,714	$ 228,749