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Commitments and Contingencies - Schedule of contract amounts represents off-balance sheet (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
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Commitment and Contingencies |  |
Amount of financial instruments represents off-balance sheet credit risk | $ 1,090,341 | $ 952,339
Commitments to originate loans |  |
Commitment and Contingencies |  |
Amount of financial instruments represents off-balance sheet credit risk | 22,141 | 34,050
Unadvanced funds on lines of credit |  |
Commitment and Contingencies |  |
Amount of financial instruments represents off-balance sheet credit risk | 636,648 | 495,796
Unadvanced funds on construction loans |  |
Commitment and Contingencies |  |
Amount of financial instruments represents off-balance sheet credit risk | 425,944 | 416,450
Letter of credit |  |
Commitment and Contingencies |  |
Amount of financial instruments represents off-balance sheet credit risk | $ 5,608 | $ 6,043

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