DERIVATIVES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Derivative [Line Items]
Derivative liability position net	$ 4,300
Derivative asset position net	1,700
Collateral received against obligations in net asset position	1,600
Collateral posted in net liability position	4,000
Interest rate swaps | Derivative designated as a cash flow hedge
Derivative [Line Items]
Notional amounts	315,000		$ 240,000
Interest rate swaps | Derivative designated as a cash flow hedge | Federal Home Loan Bank of New York
Derivative [Line Items]
Interest (income) expense on derivative	(556)	$ 65
Reduction to interest expense	(556)
Reclassified estimated decrease in interest expense	$ 1,700