INVESTMENT SECURITIES - Schedule of Investment Securities Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Amortized Cost
Five to ten years	$ 3,491
Beyond ten years	11,876
Amortized Cost	614,240	$ 623,037
Fair Value
Five to ten years	3,483
Beyond ten years	11,897
Fair Value	623,499	625,074
Amortized Cost
Held-to-maturity investment securities beyond ten years	78
Amortized Cost	7,990	10,170
Fair Value
Beyond ten years	78
Total held to maturity debt securities	8,393	$ 10,349
MBS and CMOs
Amortized Cost
MBS and CMOs	598,873
Fair Value
MBS and CMOs	608,119
MBS
Amortized Cost
MBS	7,912
Fair Value
MBS	$ 8,315