DERIVATIVES AND HEDGING ACTIVITIES - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Derivative [Line Items]
Derivatives designated as a hedging instrument	$ 0		$ 0
Liability for cash collateral received from counterparties	16,700,000		15,200,000
Receivable for cash collateral paid to counterparties	17,700,000		2,900,000
Notional amount of open interest rate swap agreements	4,228,773,000		3,696,733,000
Interest rate swaps, back-to-back [Member]
Derivative [Line Items]
Notional amount of open interest rate swap agreements	193,300,000		$ 144,100,000
Mark-to-market losses recorded	$ 494,000	$ 10,000