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Fair Value Measurements - Schedule of Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring and Non-Recurring Basis (Details) - USD ($) $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2025 | Dec. 31, 2024
Estimated Fair Value | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Loans held for sale | $ 4.2 | $ 0.9
Deferred compensation plan assets | 21.5 | 22.7
Estimated Fair Value | U.S. Treasury notes | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 233.9 | 226.9
Estimated Fair Value | State, county, and municipal securities | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 213.4 | 212.0
Estimated Fair Value | Obligations of U.S. government agencies | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 206.7 | 213.3
Estimated Fair Value | Private mortgage-backed securities | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 182.3 | 190.5
Estimated Fair Value | Corporate securities | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 227.0 | 232.9
Estimated Fair Value | Collateral-dependent loans | Fair Value Measured on a Non-recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Collateral-dependent loans | 32.8 | 97.6
Estimated Fair Value | Collateralized Loan Obligations | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 626.8 | 772.0
Estimated Fair Value | Commercial Mortgage-Backed Securities | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 947.1 | 982.8
Estimated Fair Value | Residential Mortgage Backed Securities | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 1,111.4 | 1,175.8
Estimated Fair Value | Collateralized Mortgage Obligations | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 993.6 | 1,050.9
Carrying Amount | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Collateral-dependent loans | 158.3 | 97.6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net | 0.0 |
Derivative assets | 29.1 | 44.9
Derivative liabilities | 88.9 | 133.8
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Loans held for sale | 0.0 | 0.0
Deferred compensation plan assets | 21.5 | 22.7
Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Loans held for sale | 4.2 | 0.9
Deferred compensation plan assets | 0.0 | 0.0
Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Loans held for sale | 0.0 | 0.0
Deferred compensation plan assets | 0.0 | 0.0
U.S. Treasury notes | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
U.S. Treasury notes | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 233.9 | 226.9
U.S. Treasury notes | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
State, county, and municipal securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
State, county, and municipal securities | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 213.4 | 212.0
State, county, and municipal securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Obligations of U.S. government agencies | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Obligations of U.S. government agencies | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 206.7 | 213.3
Obligations of U.S. government agencies | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Private mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Private mortgage-backed securities | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 182.3 | 190.5
Private mortgage-backed securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Corporate securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Corporate securities | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 227.0 | 232.9
Corporate securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Collateral-dependent loans | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Non-recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Collateral-dependent loans | 0.0 | 0.0
Collateral-dependent loans | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Non-recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Collateral-dependent loans | 0.0 | 0.0
Collateral-dependent loans | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Collateral-dependent loans | 32.8 | 97.6
Collateralized Loan Obligations | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Collateralized Loan Obligations | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 626.8 | 772.0
Collateralized Loan Obligations | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Commercial Mortgage-Backed Securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Commercial Mortgage-Backed Securities | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 947.1 | 982.8
Commercial Mortgage-Backed Securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Residential Mortgage Backed Securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Residential Mortgage Backed Securities | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 1,111.4 | 1,175.8
Residential Mortgage Backed Securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Collateralized Mortgage Obligations | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Collateralized Mortgage Obligations | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 993.6 | 1,050.9
Collateralized Mortgage Obligations | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Estimated Fair Value | 0.0 | 0.0
Interest Rate Swap | Estimated Fair Value | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 29.1 | 44.9
Derivative liabilities | 88.6 | 132.8
Interest Rate Swap | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 0.0 | 0.0
Derivative liabilities | 0.0 | 0.0
Interest Rate Swap | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 29.1 | 44.9
Derivative liabilities | 88.6 | 132.8
Interest Rate Swap | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 0.0 | 0.0
Derivative liabilities | 0.0 | 0.0
Interest Rate Collars | Estimated Fair Value | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative liabilities | 0.3 | 1.0
Interest Rate Collars | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative liabilities | 0.0 | 0.0
Interest Rate Collars | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative liabilities | 0.3 | 1.0
Interest Rate Collars | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative liabilities | $ 0.0 | $ 0.0

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- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. 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