SECURITIES - Contractual Maturities of Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Available-for-sale, Amortized Cost
Due in one year or less	$ 0
Due after one year through five years	4,913
Due after five years through ten years	11,236
Due after ten years	0
Total	16,149
Available-for-sale, Amortized Cost	655,542	$ 715,507
Available-for-sale, Fair Value
Due in one year or less	0
Due after one year through five years	4,871
Due after five years through ten years	11,271
Due after ten years	0
Total	16,142
Available-for-sale Securities, Total	635,333	705,539
Held-to-maturity, Amortized Cost
Due after ten years	6,191
Total	6,191
Held-to-maturity, Amortized Cost	64,530	13,275
Held-to-maturity, Fair Value
Due after ten years	6,186
Total	6,186
Held-to-maturity, fair value	63,993	13,146
Mortgage-backed securities and collateralized mortgage obligations
Available-for-sale, Amortized Cost
Amortized cost	540,268
Available-for-sale, Fair Value
Fair value	521,974
Held-to-maturity, Amortized Cost
Amortized cost	58,339
Held-to-maturity, Fair Value
Fair value	57,807
SBA guaranteed securities
Available-for-sale, Amortized Cost
Amortized cost	99,125
Available-for-sale, Amortized Cost	99,125	104,111
Available-for-sale, Fair Value
Fair value	97,217
Available-for-sale Securities, Total	$ 97,217	$ 103,292