Loans - Narrative (Details)	12 Months Ended
Dec. 31, 2025 USD ($) loan	Dec. 31, 2024 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net deferred loan costs included in loan balances	$ 12,737,000	$ 12,457,000
Loans used to collateralize borrowings from the Federal Home Loan Bank of Boston	669,541,000	626,851,000
Loans	2,394,109,000	2,340,940,000
Loans to directors, officers and employees	48,681,000	54,997,000
Interest income which would have been recognized on loans	466,000	172,000
Loans more than 90 days past due accruing interest	$ 665,000	$ 1,020,000
Number of mortgage loans in the process of foreclosure \| loan	7	3
Mortgage loans in the process of foreclosure	$ 1,754,000	$ 192,000
Home Equity Line of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of mortgage loans in the process of foreclosure \| loan	1
Mortgage loans in the process of foreclosure	$ 63,000
Commercial Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of mortgage loans in the process of foreclosure \| loan	7
Mortgage loans in the process of foreclosure	$ 3,826,000
Residential \| Term
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	739,188,000	710,807,000
Loans more than 90 days past due accruing interest	613,000	778,000
Interest rate swap agreements \| Designated as Hedging Instrument
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan adjustments	(910,000)	(560,000)
Interest rate swap agreements \| Fair Value Hedges \| Designated as Hedging Instrument
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan adjustments	(910,000)	(758,000)
Interest rate cap agreements \| Fair Value Hedges \| Designated as Hedging Instrument
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan adjustments	154,000	0
Interest rate cap agreements \| Fair Value Hedges \| Designated as Hedging Instrument \| Residential \| Term
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan adjustments	(371,000)	0
Loans pledged as collateral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 366,032,000	$ 392,562,000

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Mortgage Loans in Process of Foreclosure, Number

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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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Amount of the collateral pledged in support of federal home loan bank advances outstanding.

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Amount of fee received for commitment to originate or purchase financing receivable where likelihood of commitment being exercised is remote, to be recognized as service income.

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Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

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