GOODWILL AND OTHER INTANGIBLES - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 21, 2018	Sep. 30, 2018	Jan. 04, 2018
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 27,300		$ 27,300
Estimated fair value of the insurance segment exceeded its carrying value					17.00%
Core deposits
Finite-Lived Intangible Assets [Line Items]
Amortization	$ 102	$ 80
Insurance Services
Finite-Lived Intangible Assets [Line Items]
Goodwill			2,300
Banking and Financial Services
Finite-Lived Intangible Assets [Line Items]
Goodwill			486
Community Bank of Bergen County Merger
Finite-Lived Intangible Assets [Line Items]
Goodwill						$ 22,298
Goodwill acquired			22,300
Community Bank of Bergen County Merger | Core deposits
Finite-Lived Intangible Assets [Line Items]
Intangibles			1,300			$ 1,300
Enterprise Bank N.J.
Finite-Lived Intangible Assets [Line Items]
Goodwill				$ 2,204
Goodwill acquired			2,200
Enterprise Bank N.J. | Core deposits
Finite-Lived Intangible Assets [Line Items]
Intangibles			$ 1,100	$ 1,000