FAIR VALUE - Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financial assets:
Cash and due from financial institutions	$ 27,439	$ 29,467
Interest-earning deposits in other financial institutions	29,358	79,071
Securities available for sale	687,594	554,611
Securities held to maturity	3,000	2,501
Accrued interest receivable	4,823	5,035
Recurring
Financial assets:
Securities available for sale	687,594	554,611
Derivative Asset	10,704	14,345
Financial liabilities:
Derivative Liabilities	11,098	14,702
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and due from financial institutions	27,439	29,467
Interest-earning deposits in other financial institutions	29,358	79,071
Equity investments	2,856	2,542
Securities available for sale	20,519	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	21	0
Derivative Asset	0	0
Financial liabilities:
Demand, savings, and insured money market accounts	1,896,904	1,752,043
Time deposits	0	0
Accrued interest payable	10	11
Derivative Liabilities	0	0
Recurring | 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	667,075	554,611
Securities held to maturity	1,662	2,175
FHLBNY and FRBNY stock	0	0
Loans, net and loans held for sale	0	0
Accrued interest receivable	1,544	1,356
Derivative Asset	10,704	14,345
Financial liabilities:
Demand, savings, and insured money market accounts	0	0
Time deposits	243,299	288,398
Accrued interest payable	259	251
Derivative Liabilities	11,098	14,702
Recurring | 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	1,338	326
FHLBNY and FRBNY stock	0	0
Loans, net and loans held for sale	1,530,753	1,514,318
Accrued interest receivable	4,823	4,915
Derivative Asset	0	0
Financial liabilities:
Demand, savings, and insured money market accounts	0	0
Time deposits	0	0
Accrued interest payable	0	0
Derivative Liabilities	0	0
Recurring | Carrying Amount
Financial assets:
Cash and due from financial institutions	27,439	29,467
Interest-earning deposits in other financial institutions	29,358	79,071
Equity investments	2,856	2,542
Securities available for sale	687,594	554,611
Securities held to maturity	2,981	2,469
FHLBNY and FRBNY stock	3,562	3,150
Loans, net and loans held for sale	1,537,323	1,515,709
Accrued interest receivable	6,388	6,271
Derivative Asset	10,704	14,345
Financial liabilities:
Demand, savings, and insured money market accounts	1,896,904	1,752,043
Time deposits	241,283	285,731
Accrued interest payable	269	262
Derivative Liabilities	11,098	14,702
Recurring | Estimated Fair Value
Financial assets:
Cash and due from financial institutions	27,439	29,467
Interest-earning deposits in other financial institutions	29,358	79,071
Equity investments	2,856	2,542
Securities available for sale	687,594	554,611
Securities held to maturity	3,000	2,501
Loans, net and loans held for sale	1,530,753	1,514,318
Accrued interest receivable	6,388	6,271
Derivative Asset	10,704	14,345
Financial liabilities:
Demand, savings, and insured money market accounts	1,896,904	1,752,043
Time deposits	243,299	288,398
Accrued interest payable	269	262
Derivative Liabilities	$ 11,098	$ 14,702