DERIVATIVES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional amounts	$ 823,900	$ 193,400
Derivative liability position net	14,900
Collateral posted in net liability position	16,300
Interest rate swaps | Derivative designated as a cash flow hedge
Derivative [Line Items]
Notional amounts	290,000	240,000
Interest income (expenses) recorded on swap transactions	1,588	$ 1,100	$ (1,400)
Interest rate swaps | Derivative designated as a cash flow hedge | Federal Home Loan Bank of New York
Derivative [Line Items]
Amounts of accumulated other comprehensive income (loss) reclassified to interest expense	1,600
Interest rate swaps | Derivative designated as a cash flow hedge | Federal Home Loan Bank of New York | Forecast
Derivative [Line Items]
Amounts of accumulated other comprehensive income (loss) reclassified to interest expense	$ 157