REVENUE FROM CONTRACTS WITH CUSTOMERS - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	$ 46,128	$ 42,054	$ 42,745
Other service charges, commissions and fees	3,003	2,872	3,575
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	46,128	42,054	42,745
Debit card interchange fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	18,945	16,086	15,588
Overdraft fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	18,267	17,736	19,447
Other service charges on deposit accounts
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	8,916	8,232	7,710
Other service charges, commissions and fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	2,721	2,575	3,004
ATM fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	2,721	2,575	3,004
Other
Disaggregation of Revenue [Line Items]
Other service charges, commissions and fees	$ 282	$ 297	$ 571