DERIVATIVES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Derivative [Line Items]
Derivative liability position net	$ 0		$ 0
Derivative asset position net	21,400		21,400
Collateral received against obligations in net asset position	20,200		20,200
Collateral posted in net liability position	0		0
Interest rate swaps | Derivative designated as a cash flow hedge
Derivative [Line Items]
Notional amounts	290,000		290,000		$ 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	$ (331)	$ (374)	(1,400)	$ (653)
Reduction to interest expense			(1,400)
Reclassified estimated decrease in interest expense			$ 78