Fair Value - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, at fair value	$ 96,562	$ 104,970
Mortgage loans held for sale, at fair value	5,703	10,736
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	126,639	139,839
Available-for-sale securities, at fair value	96,562	104,970
Held-to-maturity securities, at amortized cost, net	336,879	367,938
Placement with banks	249	249
Mortgage loans held for sale, at fair value	5,703	10,736
Loans receivable, net	2,458,712	2,286,599
Accrued interest receivable	19,126	17,771
FHLBNY stock	26,620	29,182
Interest rate swap		2,005
Demand deposits	197,671	169,178
Interest-bearing deposits	1,094,017	935,382
Certificates of deposit	750,521	780,304
Advance payments by borrowers for taxes and insurance	10,942	10,349
Borrowings	536,100	596,100
Accrued interest payable	4,161	3,712
Interest rate swap		2,005
Fair Value Measurements
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	126,639	139,839
Available-for-sale securities, at fair value	96,562	104,970
Held-to-maturity securities, at amortized cost, net	329,279	355,294
Placement with banks	249	249
Mortgage loans held for sale, at fair value	5,703	10,736
Loans receivable, net	2,448,877	2,260,989
Accrued interest receivable	19,126	17,771
FHLBNY stock	26,620	29,182
Interest rate swap		2,005
Demand deposits	197,671	169,178
Interest-bearing deposits	1,094,017	935,382
Certificates of deposit	747,604	778,603
Advance payments by borrowers for taxes and insurance	10,942	10,349
Borrowings	531,758	586,562
Accrued interest payable	4,161	3,712
Interest rate swap		2,005
Fair Value Measurements | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	126,639	139,839
Available-for-sale securities, at fair value	3,172	3,203
FHLBNY stock	26,620	29,182
Demand deposits	197,671	169,178
Interest-bearing deposits	1,094,017	935,382
Fair Value Measurements | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, at fair value	93,390	101,767
Held-to-maturity securities, at amortized cost, net	329,279	355,294
Placement with banks	249	249
Mortgage loans held for sale, at fair value	5,703	10,736
Accrued interest receivable	19,126	17,771
Interest rate swap		2,005
Certificates of deposit	747,604	778,603
Advance payments by borrowers for taxes and insurance	10,942	10,349
Borrowings	531,758	586,562
Accrued interest payable	4,161	3,712
Interest rate swap		2,005
Fair Value Measurements | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans receivable, net	$ 2,448,877	$ 2,260,989