SECURITIES - Contractual Maturities of Securities Available for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Available for Sale, Amortized Cost
Within one year	$ 13,327
One through five years	50,056
Six through ten years	129,180
After ten years	144,094
Amortized Cost, Equity securities	4,689
Amortized Cost	908,055	$ 905,857
Available for Sale, Fair Value
Within one year	13,451
One through five years	52,486
Six through ten years	137,543
After ten years	152,934
Equity securities	4,689
Fair Value	937,719	925,279
Mortgage-backed securities-residential (Government Sponsored Entity)
Available for Sale, Amortized Cost
Debt securities without single maturity date	348,661
Amortized Cost	348,661	332,525
Available for Sale, Fair Value
Debt securities without single maturity date	354,998
Fair Value	354,998	334,080
Collateralized mortgage obligations (Government Sponsored Entity)
Available for Sale, Amortized Cost
Debt securities without single maturity date	218,048
Amortized Cost	218,048	228,621
Available for Sale, Fair Value
Debt securities without single maturity date	221,618
Fair Value	$ 221,618	$ 228,749