FAIR VALUES - Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financial assets:
Cash and due from financial institutions	$ 29,467	$ 25,203
Interest-earning deposits in other financial institutions	79,071	96,701
Securities available for sale	554,611	284,090
Securities held to maturity	2,469	3,115
Loans, net and loans held for sale	1,515,539	1,285,741
Accrued interest receivable	5,035	3,684
Deposits:
Time deposits	285,731	161,176
Carrying Amount
Financial assets:
Cash and due from financial institutions	29,467	25,203
Interest-earning deposits in other financial institutions	79,071	96,701
Equity investments	2,542	2,174
Securities available for sale	554,611	284,090
Securities held to maturity	2,469	3,115
FHLBNY and FRBNY stock	3,150	3,099
Loans, net and loans held for sale	1,515,709	1,286,926
Accrued interest receivable	6,271	4,633
Derivative assets	14,702	6,466
Deposits:
Demand, savings, and insured money market accounts	1,752,043	1,410,962
Time deposits	285,731	161,176
Accrued interest payable	262	299
Derivative liabilities	15,059	6,831
Estimated Fair Value
Financial assets:
Cash and due from financial institutions	29,467	25,203
Interest-earning deposits in other financial institutions	79,071	96,701
Equity investments	2,542	2,174
Securities available for sale	554,611	284,090
Securities held to maturity	2,501	3,139
Loans, net and loans held for sale	1,514,318	1,285,215
Accrued interest receivable	6,271	4,633
Derivative assets	14,702	6,466
Deposits:
Demand, savings, and insured money market accounts	1,752,043	1,410,962
Time deposits	288,398	163,761
Accrued interest payable	262	299
Derivative liabilities	15,059	6,831
Estimated Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and due from financial institutions	29,467	25,203
Interest-earning deposits in other financial institutions	79,071	96,701
Equity investments	2,542	2,174
Securities available for sale	0	0
Securities held to maturity	0	0
FHLBNY and FRBNY stock	0	0
Loans, net and loans held for sale	0	0
Accrued interest receivable	0	63
Derivative assets	0	0
Deposits:
Demand, savings, and insured money market accounts	1,752,043	1,410,962
Time deposits	0	0
Accrued interest payable	11	27
Derivative liabilities	0	0
Estimated Fair Value | Significant Other Observable Inputs (Level 2)
Financial assets:
Cash and due from financial institutions	0	0
Interest-earning deposits in other financial institutions	0	0
Equity investments	0	0
Securities available for sale	554,611	284,090
Securities held to maturity	2,175	2,094
FHLBNY and FRBNY stock	0	0
Loans, net and loans held for sale	0	0
Accrued interest receivable	1,356	885
Derivative assets	14,702	6,466
Deposits:
Demand, savings, and insured money market accounts	0	0
Time deposits	288,398	163,761
Accrued interest payable	251	272
Derivative liabilities		6,466
Estimated Fair Value | Significant Unobservable Inputs (Level 3)
Financial assets:
Cash and due from financial institutions	0	0
Interest-earning deposits in other financial institutions	0	0
Equity investments	0	0
Securities available for sale	0	0
Securities held to maturity	326	1,045
FHLBNY and FRBNY stock	0	0
Loans, net and loans held for sale	1,514,318	1,285,215
Accrued interest receivable	4,915	3,685
Derivative assets	0	0
Deposits:
Demand, savings, and insured money market accounts	0	0
Time deposits	0	0
Accrued interest payable	$ 0	0
Derivative liabilities		$ 365