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Loans and Allowance for Credit Losses on Loans - Major Loan Segments and Classes (Details) - USD ($) | Mar. 31, 2026 | Dec. 31, 2025 | Jun. 30, 2025 | Mar. 31, 2025 | Dec. 31, 2024 | Jun. 30, 2024
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Loans and Allowance for Credit Losses on Loans [Abstract] |  |  |  |  |  |  |
Total gross loans | [1],[2] | $ 1,747,703,000 |  | $ 1,627,406,000 |  |  |
Allowance for credit losses on loans |  | (21,778,000) | $ (21,334,000) | (20,146,000) | $ (21,196,000) | $ (20,191,000) | $ (19,244,000)
Net loans receivable |  | 1,725,925,000 |  | 1,607,260,000 |  |  |
Loan balances include net deferred fees/costs |  | (490,000) |  | (567,000) |  |  |
Accrued interest receivable |  | 8,000,000 |  | 7,000,000 |  |  |
Commercial Portfolio [Member] |  |  |  |  |  |  |
Loans and Allowance for Credit Losses on Loans [Abstract] |  |  |  |  |  |  |
Total gross loans |  | 134,981,000 |  | 116,769,000 |  |  |
Allowance for credit losses on loans |  | (2,754,000) | (2,632,000) | (2,278,000) | (2,156,000) | (2,079,000) | (2,077,000)
Residential Real Estate [Member] | Residential Portfolio [Member] |  |  |  |  |  |  |
Loans and Allowance for Credit Losses on Loans [Abstract] |  |  |  |  |  |  |
Total gross loans |  | 415,749,000 |  | 417,719,000 |  |  |
Allowance for credit losses on loans |  | (4,615,000) | (4,625,000) | (4,613,000) | (4,596,000) | (4,531,000) | (4,237,000)
Real Estate [Member] | Commercial Real Estate Portfolio [Member] |  |  |  |  |  |  |
Loans and Allowance for Credit Losses on Loans [Abstract] |  |  |  |  |  |  |
Total gross loans |  | 1,151,349,000 |  | 1,054,504,000 |  |  |
Allowance for credit losses on loans |  | (13,765,000) | (13,419,000) | (12,614,000) | (13,799,000) | (12,933,000) | (12,218,000)
Home Equity [Member] | Consumer Portfolio [Member] |  |  |  |  |  |  |
Loans and Allowance for Credit Losses on Loans [Abstract] |  |  |  |  |  |  |
Total gross loans |  | 41,779,000 |  | 34,103,000 |  |  |
Allowance for credit losses on loans |  | (344,000) | (340,000) | (260,000) | (240,000) | (234,000) | (212,000)
Consumer [Member] | Consumer Portfolio [Member] |  |  |  |  |  |  |
Loans and Allowance for Credit Losses on Loans [Abstract] |  |  |  |  |  |  |
Total gross loans |  | 3,845,000 |  | 4,311,000 |  |  |
Allowance for credit losses on loans |  | $ (300,000) | $ (318,000) | $ (381,000) | $ (405,000) | $ (414,000) | $ (500,000)
[1] | Loan balances exclude accrued interest receivable of $8.0 million and $7.0 million at March 31, 2026 and June 30, 2025, respectively, which is included in accrued interest receivable in the consolidated statement of financial condition.
[2] | Loan balances include net deferred fees/(costs) of ($490,000) and ($567,000) at March 31, 2026 and June 30, 2025, respectively.

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- Definition Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements. + References No definition available. + Details
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