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Off-Balance Sheet Credit Risk (Details) - USD ($) $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2025 | Dec. 31, 2024
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
General settlement period of securities transactions | 1 day |
Fair value of securities accepted as collateral permitted to sell or repledge | $ 2,200.0 | $ 2,000.0
Fair value of collateral securities sold or repledged | 747.3 | 580.2
Outstanding commitments to originate loans | 358.6 | 207.2
Letters of credit outstanding | 81.6 | 40.6
Unfunded Commitment [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Unused lines of credit to commercial and consumer borrowers | 30.2 | 30.7
Unused Lines Of Credit [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Unused lines of credit to commercial and consumer borrowers | $ 5,500.0 | $ 5,400.0
Standby Letters of Credit [Member] | Maximum [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Letters of credit, expiration period | 1 year |

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