Fair Value - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, at fair value	$ 116,044	$ 119,902
Held-to-maturity securities, at amortized cost, net		461,748
Mortgage loans held for sale, at fair value	7,860	9,980
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	134,724	139,190
Available-for-sale securities, at fair value	116,044	119,902
Held-to-maturity securities, at amortized cost, net	452,955	461,748
Placements with banks	249	249
Mortgage loans held for sale, at fair value	7,860	9,980
Loans receivable, net	1,981,428	1,895,886
Accrued interest receivable	18,063	18,010
FHLBNY stock	23,892	19,377
Demand deposits	191,541	185,151	[1]
Interest-bearing deposits	765,977	721,643	[1]
Certificates of deposit	628,266	600,826
Advance payments by borrowers for taxes and insurance	13,245	10,778
Borrowings	680,421	684,421
Accrued interest payable	4,218	11,965
Interest rate swap	$ 1,496	$ 4,435
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Loans and Leases Receivable, Net Amount	Loans and Leases Receivable, Net Amount
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	$ 134,724	$ 139,190
Available-for-sale securities, at fair value	116,044	119,902
Held-to-maturity securities, at amortized cost, net	438,113	450,042
Placements with banks	249	249
Mortgage loans held for sale, at fair value	7,860	9,980
Loans receivable, net	1,935,063	1,844,507
Accrued interest receivable	18,063	18,010
FHLBNY stock	23,892	19,377
Demand deposits	191,541	185,151	[1]
Interest-bearing deposits	765,977	721,643	[1]
Certificates of deposit	621,250	594,234
Advance payments by borrowers for taxes and insurance	13,245	10,778
Borrowings	667,493	674,155
Accrued interest payable	4,218	11,965
Interest rate swap	1,496	4,435
Fair Value Measurements | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	134,724	139,190
Available-for-sale securities, at fair value	2,780	3,320
FHLBNY stock	23,892	19,377
Demand deposits	191,541	185,151	[1]
Interest-bearing deposits	765,977	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	113,264	116,582
Held-to-maturity securities, at amortized cost, net	438,113	450,042
Placements with banks	249	249
Mortgage loans held for sale, at fair value	7,860	9,980
Accrued interest receivable	18,063	18,010
Certificates of deposit	621,250	594,234
Advance payments by borrowers for taxes and insurance	13,245	10,778
Borrowings	667,493	674,155
Accrued interest payable	4,218	11,965
Interest rate swap	1,496	4,435
Fair Value Measurements | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans receivable, net	$ 1,935,063	$ 1,844,507

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