LOANS - Impaired Loans Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Nonaccrual loans	$ 47,892	$ 66,673
Accruing loans past due 90 days or more	375	1,169
Restructured loans - nonaccrual	9,446	10,133
Restructured loans - accruing	13,093	16,518
Total nonperforming loans	70,806	94,493
Originated
Financing Receivable, Impaired [Line Items]
Nonaccrual loans	43,797	32,805
Accruing loans past due 90 days or more	375	1,169
Restructured loans - nonaccrual	8,063	6,959
Restructured loans - accruing	4,255	5,267
Total nonperforming loans	56,490	46,200
Acquired
Financing Receivable, Impaired [Line Items]
Nonaccrual loans	4,095	33,868
Restructured loans - nonaccrual	1,383	3,174
Restructured loans - accruing	8,838	11,251
Total nonperforming loans	$ 14,316	$ 48,293