v3.25.2
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