REVENUE FROM CONTRACTS WITH CUSTOMERS - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	$ 50,792	$ 46,128	$ 42,054
Other service charges, commissions and fees	3,913	3,059	2,883
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	50,792	46,128	42,054
Debit card interchange fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	18,909	18,945	16,086
Overdraft fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	21,710	18,267	17,736
Other service charges on deposit accounts
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	10,173	8,916	8,232
Other service charges, commissions and fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	3,228	2,721	2,575
ATM fees
Disaggregation of Revenue [Line Items]
ASC 606 Revenue Items	3,228	2,721	2,575
Other
Disaggregation of Revenue [Line Items]
Other service charges, commissions and fees	$ 685	$ 338	$ 308