DERIVATIVES AND HEDGING ACTIVITIES - Derivatives Fair Value and Balance Sheet Classification (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Asset derivatives	$ 83,304	$ 36,099
Liability derivatives	85,193	36,822
Interest rate swaps | Derivatives designated as hedging instruments: | Other assets
Derivatives, Fair Value [Line Items]
Asset derivatives	0	0
Interest rate swaps | Derivatives designated as hedging instruments: | Other liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	228	0
Interest rate swaps | Derivatives not designated as hedging instruments: | Other assets
Derivatives, Fair Value [Line Items]
Asset derivatives	83,255	36,089
Interest rate swaps | Derivatives not designated as hedging instruments: | Other liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	84,590	36,580
Risk participation agreements | Derivatives not designated as hedging instruments: | Other assets
Derivatives, Fair Value [Line Items]
Asset derivatives	49	10
Risk participation agreements | Derivatives not designated as hedging instruments: | Other liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	$ 375	$ 242