ACQUISITIONS (Summary of Loans Acquired in Accordance with ASC 310-30) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Jan. 04, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Interest component of expected cash flows (accretable difference)	$ (460)	$ (539)	$ (769)		$ 0
Community Bank of Bergen County Merger
Business Acquisition [Line Items]
Fair value of acquired loans				$ 236,070
Community Bank of Bergen County Merger | Loans acquired with credit deterioration
Business Acquisition [Line Items]
Contractually required principal and interest at acquisition				6,289
Contractual cash flows not expected to be collected (non-accretable difference)				1,819
Expected cash flows at acquisition				4,470
Interest component of expected cash flows (accretable difference)				(846)
Fair value of acquired loans				$ 3,624