FAIR VALUE - Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial Assets [Abstract]
Cash and due from financial institutions	$ 25,473	$ 27,966
Interest-bearing deposits in other financial institutions	5,531	2,763
Securities held to maturity	3,627	3,776
Loans, net	1,298,521	1,290,663
Accrued interest receivable	3,618	3,758
Financial liabilities [Abstract]
Securities sold under agreements to repurchase	10,000	10,000
FHLBNY overnight advances	0	57,700
FHLBNY term advances	0	2,000
Recurring
Financial Assets [Abstract]
Securities available for sale	278,984	293,091
Derivative assets	1,820	974
Financial liabilities [Abstract]
Derivative liabilities	1,870	1,049
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets [Abstract]
Cash and due from financial institutions	25,473	27,966
Interest-bearing deposits in other financial institutions	5,531	2,763
Trading assets	1,225	1,192
Securities available for sale	0	0
Securities held to maturity	0	0
FHLBNY and FRBNY stock	0	0
Loans, net	0	0
Loans held for sale		0
Accrued interest receivable	0	1
Derivative assets	0	0
Financial liabilities [Abstract]
Demand, savings, and insured money market accounts	1,401,753	1,349,084
Time deposits	0	0
Securities sold under agreements to repurchase	0	0
FHLBNY overnight advances		0
FHLBNY term advances		0
Accrued interest payable	24	24
Derivative liabilities	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Financial Assets [Abstract]
Cash and due from financial institutions	0	0
Interest-bearing deposits in other financial institutions	0	0
Trading assets	0	0
Securities available for sale	278,984	293,091
Securities held to maturity	1,822	1,830
FHLBNY and FRBNY stock	0	0
Loans, net	0	0
Loans held for sale		542
Accrued interest receivable	1,006	867
Derivative assets	1,820	974
Financial liabilities [Abstract]
Demand, savings, and insured money market accounts	0	0
Time deposits	116,677	118,598
Securities sold under agreements to repurchase	10,019	10,058
FHLBNY overnight advances		57,700
FHLBNY term advances		2,001
Accrued interest payable	95	124
Derivative liabilities	1,820	974
Recurring | Significant Unobservable Inputs (Level 3)
Financial Assets [Abstract]
Cash and due from financial institutions	0	0
Interest-bearing deposits in other financial institutions	0	0
Trading assets	0	0
Securities available for sale	0	0
Securities held to maturity	1,085	1,946
FHLBNY and FRBNY stock	0	0
Loans, net	1,272,169	1,289,584
Loans held for sale		0
Accrued interest receivable	3,618	3,774
Derivative assets	0	0
Financial liabilities [Abstract]
Demand, savings, and insured money market accounts	0	0
Time deposits	0	0
Securities sold under agreements to repurchase	0	0
FHLBNY overnight advances		0
FHLBNY term advances		0
Accrued interest payable	0	0
Derivative liabilities	50	75
Recurring | Carrying Amount
Financial Assets [Abstract]
Cash and due from financial institutions	25,473	27,966
Interest-bearing deposits in other financial institutions	5,531	2,763
Trading assets	1,225	1,192
Securities available for sale	278,984	293,091
Securities held to maturity	3,640	3,781
FHLBNY and FRBNY stock	3,097	5,784
Loans, net	1,298,711	1,291,205
Loans held for sale		542
Accrued interest receivable	4,624	4,642
Derivative assets	1,820	974
Financial liabilities [Abstract]
Demand, savings, and insured money market accounts	1,401,753	1,349,084
Time deposits	116,447	118,362
Securities sold under agreements to repurchase	10,000	10,000
FHLBNY overnight advances		57,700
FHLBNY term advances		2,000
Accrued interest payable	119	148
Derivative liabilities	1,870	1,049
Recurring | Estimated Fair Value
Financial Assets [Abstract]
Cash and due from financial institutions	25,473	27,966
Interest-bearing deposits in other financial institutions	5,531	2,763
Trading assets	1,225	1,192
Securities available for sale	278,984	293,091
Securities held to maturity	2,907	3,776
Loans, net	1,272,169	1,289,584
Loans held for sale		542
Accrued interest receivable	4,624	4,642
Derivative assets	1,820	974
Financial liabilities [Abstract]
Demand, savings, and insured money market accounts	1,401,753	1,349,084
Time deposits	116,677	118,598
Securities sold under agreements to repurchase	10,019	10,058
FHLBNY overnight advances		57,700
FHLBNY term advances		2,001
Accrued interest payable	119	148
Derivative liabilities	$ 1,870	$ 1,049