Fair Value - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, at fair value	$ 113,125	$ 119,902
Held-to-maturity securities, at amortized cost, net		461,748
Mortgage loans held for sale, at fair value	37,764	9,980
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	103,166	139,190
Available-for-sale securities, at fair value	113,125	119,902
Held-to-maturity securities, at amortized cost, net	442,113	461,748
Placements with banks	249	249
Mortgage loans held for sale, at fair value	37,764	9,980
Loans receivable, net	2,022,173	1,895,886
Accrued interest receivable	17,441	18,010
FHLBNY stock	23,972	19,377
Interest rate swap	790	4,435
Demand deposits	178,125	185,151	[1]
Interest-bearing deposits	803,072	721,643	[1]
Certificates of deposit	624,900	600,826
Advance payments by borrowers for taxes and insurance	10,838	10,778
Borrowings	680,421	684,421
Accrued interest payable	6,820	11,965
Interest rate swap	$ 790	$ 4,435
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Financing Receivable, after Allowance for Credit Loss	Financing Receivable, after Allowance for Credit Loss
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities	Other Liabilities
Fair Value Measurements
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 103,166	$ 139,190
Available-for-sale securities, at fair value	113,125	119,902
Held-to-maturity securities, at amortized cost, net	425,645	450,042
Placements with banks	249	249
Mortgage loans held for sale, at fair value	37,764	9,980
Loans receivable, net	1,980,112	1,844,507
Accrued interest receivable	17,441	18,010
FHLBNY stock	23,972	19,377
Interest rate swap	790	4,435
Demand deposits	178,125	185,151	[1]
Interest-bearing deposits	803,072	721,643	[1]
Certificates of deposit	618,206	594,234
Advance payments by borrowers for taxes and insurance	10,838	10,778
Borrowings	667,493	674,155
Accrued interest payable	6,820	11,965
Interest rate swap	790	4,435
Fair Value Measurements | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	103,166	139,190
Available-for-sale securities, at fair value	2,796	3,320
FHLBNY stock	23,972	19,377
Demand deposits	178,125	185,151	[1]
Interest-bearing deposits	803,072	721,643	[1]
Fair Value Measurements | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, at fair value	110,329	116,582
Held-to-maturity securities, at amortized cost, net	425,645	450,042
Placements with banks	249	249
Mortgage loans held for sale, at fair value	37,764	9,980
Accrued interest receivable	17,441	18,010
Interest rate swap	790	4,435
Certificates of deposit	618,206	594,234
Advance payments by borrowers for taxes and insurance	10,838	10,778
Borrowings	667,493	674,155
Accrued interest payable	6,820	11,965
Interest rate swap	790	4,435
Fair Value Measurements | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans receivable, net	$ 1,980,112	$ 1,844,507

[1] As of December 31, 2023, $58.2 million were reclassified from demand deposits to interest-bearing deposits.