REVENUE FROM CONTRACTS WITH CUSTOMERS - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	$ 10,228	$ 10,563
Other service charges, commissions and fees	719	709
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	10,228	10,563
Debit card interchange fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	4,210	4,046
Overdraft fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	4,108	4,444
Other service charges on deposit accounts
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	1,910	2,073
Other service charges, commissions and fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	661	674
ATM fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	661	674
Other
Disaggregation of Revenue [Line Items]
Other service charges, commissions and fees	$ 58	$ 35