DERIVATIVES AND HEDGING ACTIVITIES - Non-designated Hedges Text description (Details)	Dec. 31, 2020 USD ($) derivativeContract derivativeContractsHeld	Dec. 31, 2019 USD ($) derivativeContractsHeld derivativeContract
Derivative [Line Items]
Derivative notional amount	$ 57,400,000	$ 58,800,000
Derivatives - interest rate swaps
Derivative [Line Items]
Derivative notional amount	$ 100,000,000
Derivatives - interest rate swaps | Derivatives not designated as hedging instruments:
Derivative [Line Items]
Derivative number of instruments | derivativeContractsHeld	208	198
Derivative notional amount	$ 1,700,000,000	$ 1,600,000,000
Foreign exchange contracts | Derivatives not designated as hedging instruments:
Derivative [Line Items]
Derivative number of instruments | derivativeContract	0	0
Risk participation agreements - executed by other financial institutions | Derivatives not designated as hedging instruments:
Derivative [Line Items]
Derivative number of instruments | derivativeContractsHeld	7	7
Risk participation agreements - executed by the Bank | Derivatives not designated as hedging instruments:
Derivative [Line Items]
Derivative number of instruments | derivativeContractsHeld	5	4
Derivative notional amount	$ 30,200,000	$ 20,500,000