FAIR VALUE - Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financial Assets [Abstract]
Cash and due from financial institutions	$ 34,572	$ 28,205
Interest-bearing deposits in other financial institutions	21,806	45,957
Securities available for sale	312,226	303,402
Securities held to maturity	3,861	4,912
Loans, net	1,273,119	1,186,037
Accrued interest receivable	3,448	3,192
Financial liabilities [Abstract]
Securities sold under agreements to repurchase	10,000	27,606
FHLBNY term advances	9,009	9,093
Recurring
Financial Assets [Abstract]
Securities available for sale	312,226	303,402
Derivative assets	670	693
Financial liabilities [Abstract]
Derivative liabilities	741	761
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets [Abstract]
Cash and due from financial institutions	34,572	28,205
Interest-bearing deposits in other financial institutions	21,806	45,957
Trading assets	909	774
Securities available for sale	194	170
Securities held to maturity	0	0
FHLBNY and FRBNY stock	0	0
Loans, net	0	0
Loans held for sale	0	0
Accrued interest receivable	2	9
Derivative assets	0	0
Financial liabilities [Abstract]
Demand, savings, and insured money market accounts	1,410,836	1,312,237
Time deposits	0	0
Securities sold under agreements to repurchase	0	0
FHLBNY term advances	0	0
Accrued interest payable	21	25
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	312,032	302,982
Securities held to maturity	1,831	981
FHLBNY and FRBNY stock	0	0
Loans, net	0	0
Loans held for sale	1,246	412
Accrued interest receivable	1,050	784
Derivative assets	670	693
Financial liabilities [Abstract]
Demand, savings, and insured money market accounts	0	0
Time deposits	126,445	144,460
Securities sold under agreements to repurchase	10,117	27,880
FHLBNY term advances	9,030	9,189
Accrued interest payable	163	185
Derivative liabilities	670	693
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	250
Securities held to maturity	2,030	3,931
FHLBNY and FRBNY stock	0	0
Loans, net	1,277,896	1,205,814
Loans held for sale	0	0
Accrued interest receivable	3,464	3,207
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 term advances	0	0
Accrued interest payable	0	0
Derivative liabilities	71	68
Recurring | Carrying Amount
Financial Assets [Abstract]
Cash and due from financial institutions	34,572	28,205
Interest-bearing deposits in other financial institutions	21,806	45,957
Trading assets	909	774
Securities available for sale	312,226	303,402
Securities held to maturity	3,865	4,705
FHLBNY and FRBNY stock	3,497	4,041
Loans, net	1,273,119	1,186,037
Loans held for sale	1,246	412
Accrued interest receivable	4,516	4,000
Derivative assets	670	693
Financial liabilities [Abstract]
Demand, savings, and insured money market accounts	1,410,836	1,312,237
Time deposits	126,182	144,106
Securities sold under agreements to repurchase	10,000	27,606
FHLBNY term advances	9,009	9,093
Accrued interest payable	184	210
Derivative liabilities	741	761
Recurring | Estimated Fair Value
Financial Assets [Abstract]
Cash and due from financial institutions	34,572	28,205
Interest-bearing deposits in other financial institutions	21,806	45,957
Trading assets	909	774
Securities available for sale	312,226	303,402
Securities held to maturity	3,861	4,912
Loans, net	1,277,896	1,205,814
Loans held for sale	1,246	412
Accrued interest receivable	4,516	4,000
Derivative assets	670	693
Financial liabilities [Abstract]
Demand, savings, and insured money market accounts	1,410,836	1,312,237
Time deposits	126,445	144,460
Securities sold under agreements to repurchase	10,117	27,880
FHLBNY term advances	9,030	9,189
Accrued interest payable	184	210
Derivative liabilities	$ 741	$ 761