Fair Value of Financial Instruments - Carrying Amounts and Estimated Fair Values of Selected Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Securities held-to-maturity, amortized cost	$ 57,890	$ 57,832
Securities available for sale, fair value	821,445	647,974
Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	6,998	1,319
Interest rate swaps	703	(2,629)
Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	7,904	7,914
Securities available for sale, fair value	596,661	404,460
Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	49,986	49,918
Securities available for sale, fair value	224,784	243,514
Reported Value Measurement [Member]
Cash and due from banks	145,971	157,388
Loans	6,718,806	6,704,674
FHLB-NY stock	41,630	43,439
Accrued interest receivable	43,803	44,041
Deposits	6,357,020	6,136,355
Borrowings	971,827	1,020,895
Accrued interest payable	4,675	4,755
Reported Value Measurement [Member] \| Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	6,998	1,319
Interest rate swaps	42,520	60,987
Reported Value Measurement [Member] \| Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	7,904	7,914
Securities available for sale, fair value	596,661	404,460
Reported Value Measurement [Member] \| Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	49,986	49,918
Securities available for sale, fair value	224,784	243,514
Estimate of Fair Value Measurement [Member]
Cash and due from banks	145,971	157,388
Loans	6,702,618	6,793,885
FHLB-NY stock	41,630	43,439
Accrued interest receivable	43,803	44,041
Deposits	6,361,050	6,141,775
Borrowings	973,198	1,017,573
Accrued interest payable	4,675	4,755
Estimate of Fair Value Measurement [Member] \| Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	6,998	1,319
Interest rate swaps	42,520	60,987
Estimate of Fair Value Measurement [Member] \| Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	8,848	8,991
Securities available for sale, fair value	596,661	404,460
Estimate of Fair Value Measurement [Member] \| Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	53,598	54,538
Securities available for sale, fair value	224,784	243,514
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and due from banks	145,971	157,388
Loans	0	0
FHLB-NY stock	0	0
Accrued interest receivable	2	2
Deposits	5,336,405	4,997,994
Borrowings	0	0
Accrued interest payable	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	0	0
Interest rate swaps	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	0	0
Securities available for sale, fair value	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	0	0
Securities available for sale, fair value	12,585	12,703
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Cash and due from banks	0	0
Loans	0	0
FHLB-NY stock	41,630	43,439
Accrued interest receivable	1,705	1,389
Deposits	1,024,645	1,143,781
Borrowings	923,384	974,437
Accrued interest payable	4,675	4,755
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	6,998	1,319
Interest rate swaps	42,520	60,987
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	8,848	8,991
Securities available for sale, fair value	596,661	404,460
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	0	0
Securities available for sale, fair value	210,704	229,516
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Cash and due from banks	0	0
Loans	6,702,618	6,793,885
FHLB-NY stock	0	0
Accrued interest receivable	42,096	42,650
Deposits	0	0
Borrowings	49,814	43,136
Accrued interest payable	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Interest Rate Swap [Member]
Interest Rate Swaps, Net Amount	0	0
Interest rate swaps	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	0	0
Securities available for sale, fair value	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	53,598	54,538
Securities available for sale, fair value	$ 1,495	$ 1,295

Fair value portion of accrued interest payable.

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Fair value portion of accrued interest receivable.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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