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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 | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2023 | Mar. 31, 2022 | Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net | $ 0.0 | $ 0.0 |
Derivative assets | 43.1 |  | $ 45.2
Derivative liabilities | 126.7 |  | 159.6
Write downs | (0.1) | $ 0.0 |
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 | 0.0 |  | 0.0
Deferred compensation plan liabilities | 0.0 |  | 0.0
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 | 8.5 |  | 6.9
Deferred compensation plan assets | 17.3 |  | 18.7
Deferred compensation plan liabilities | 17.3 |  | 18.7
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 | 7.5 |  | 5.5
Deferred compensation plan assets | 0.0 |  | 0.0
Deferred compensation plan liabilities | 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] |  |  |
Investment debt securities available-for-sale | 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] |  |  |
Investment debt securities available-for-sale | 223.2 |  | 642.7
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] |  |  |
Investment debt securities available-for-sale | 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] |  |  |
Investment debt securities available-for-sale | 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] |  |  |
Investment debt securities available-for-sale | 221.1 |  | 263.7
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] |  |  |
Investment debt securities available-for-sale | 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] |  |  |
Investment debt securities available-for-sale | 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] |  |  |
Investment debt securities available-for-sale | 174.1 |  | 198.9
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] |  |  |
Investment debt securities available-for-sale | 0.0 |  | 0.0
U.S. agency residential & commercial mortgage-backed securities & 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] |  |  |
Investment debt securities available-for-sale | 0.0 |  | 0.0
U.S. agency residential & commercial mortgage-backed securities & 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] |  |  |
Investment debt securities available-for-sale | 3,858.4 |  | 4,259.7
U.S. agency residential & commercial mortgage-backed securities & 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] |  |  |
Investment debt securities available-for-sale | 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] |  |  |
Investment debt securities available-for-sale | 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] |  |  |
Investment debt securities available-for-sale | 225.1 |  | 228.0
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] |  |  |
Investment debt securities available-for-sale | 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] |  |  |
Investment debt securities available-for-sale | 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] |  |  |
Investment debt securities available-for-sale | 233.5 |  | 241.5
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] |  |  |
Investment debt securities available-for-sale | 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 | 59.5 |  | 39.1
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] |  |  |
Investment debt securities available-for-sale | 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] |  |  |
Investment debt securities available-for-sale | 1,113.9 |  | 1,111.6
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] |  |  |
Investment debt securities available-for-sale | 0.0 |  | 0.0
Estimated Fair Value |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Investment debt securities available-for-sale | 6,049.3 |  | 6,946.1
Derivative assets | 43.1 |  | 45.2
Derivative liabilities | 126.7 |  | 159.6
Deferred compensation plan assets | 17.3 |  | 18.7
Deferred compensation plan liabilities | 17.3 |  | 18.7
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 | 16.0 |  | 12.4
Deferred compensation plan assets | 17.3 |  | 18.7
Deferred compensation plan liabilities | 17.3 |  | 18.7
Estimated Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Investment debt securities available-for-sale | 0.0 |  | 0.0
Derivative assets | 0.0 |  | 0.0
Derivative liabilities | 0.0 |  | 0.0
Deferred compensation plan assets | 0.0 |  | 0.0
Deferred compensation plan liabilities | 0.0 |  | 0.0
Estimated Fair Value | Significant Other Observable Inputs (Level 2) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Investment debt securities available-for-sale | 6,049.3 |  | 6,946.1
Derivative assets | 43.1 |  | 45.2
Derivative liabilities | 126.7 |  | 159.6
Deferred compensation plan assets | 17.3 |  | 18.7
Deferred compensation plan liabilities | 17.3 |  | 18.7
Estimated Fair Value | Significant Unobservable Inputs (Level 3) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Investment debt securities available-for-sale | 0.0 |  | 0.0
Derivative assets | 0.0 |  | 0.0
Derivative liabilities | 0.0 |  | 0.0
Deferred compensation plan assets | 0.0 |  | 0.0
Deferred compensation plan liabilities | 0.0 |  | 0.0
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] |  |  |
Investment debt securities available-for-sale | 223.2 |  | 642.7
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] |  |  |
Investment debt securities available-for-sale | 221.1 |  | 263.7
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] |  |  |
Investment debt securities available-for-sale | 174.1 |  | 198.9
Estimated Fair Value | U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations | Fair Value Measured on a Recurring Basis |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Investment debt securities available-for-sale | 3,858.4 |  | 4,259.7
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] |  |  |
Investment debt securities available-for-sale | 225.1 |  | 228.0
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] |  |  |
Investment debt securities available-for-sale | 233.5 |  | 241.5
Estimated Fair Value | 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 | 59.5 |  | 39.1
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] |  |  |
Investment debt securities available-for-sale | 1,113.9 |  | 1,111.6
Carrying Amount |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Investment debt securities available-for-sale | 6,049.3 |  | 6,946.1
Derivative assets | 43.1 |  | 45.2
Derivative liabilities | 126.7 |  | 159.6
Deferred compensation plan assets | 17.3 |  | 18.7
Deferred compensation plan liabilities | 17.3 |  | 18.7
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 | 59.5 |  | 39.1
Long-lived assets to be disposed of by sale | $ 5.0 |  | $ 5.5
Long-Lived Assets Held-for-sale, Description | 5.1 million |  | 5.7 million
Change During Period | Fair Value Measured on a Non-recurring Basis |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Long-lived assets to be disposed of by sale | $ 0.1 |  | $ 0.2
Interest Rate Swap |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Derivative assets | 42.8 |  | 45.1
Derivative liabilities | 126.6 |  | 159.6
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 | 42.8 |  | 45.1
Derivative liabilities | 122.7 |  | 154.2
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 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 | 42.8 |  | 45.1
Derivative liabilities | 122.7 |  | 154.2
Interest Rate Lock Commitments | 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 |  |
Interest Rate Lock Commitments | 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 | 0.3 |  |
Interest Rate Lock Commitments | 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 |  |
Interest Rate Lock Commitments | 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 | 0.3 |  |
Forward Contracts | 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
Derivative liabilities | 0.0 |  |
Forward Contracts | 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 |  |  | 0.1
Derivative liabilities | 0.1 |  |
Forward Contracts | 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
Derivative liabilities | 0.0 |  |
Forward Contracts | 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 |  |  | 0.1
Derivative liabilities | 0.1 |  |
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 assets |  |  | 0.0
Derivative liabilities | 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 assets |  |  | 5.4
Derivative liabilities | 3.9 |  |
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 assets |  |  | 0.0
Derivative liabilities | 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 assets |  |  | 5.4
Derivative liabilities | 3.9 |  |
Long-lived assets to be disposed of by sale | 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] |  |  |
Long-lived assets to be disposed of by sale | 0.0 |  | 0.0
Long-lived assets to be disposed of by sale | 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] |  |  |
Long-lived assets to be disposed of by sale | 0.0 |  | 0.0
Long-lived assets to be disposed of by sale | 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] |  |  |
Long-lived assets to be disposed of by sale | 5.0 |  | 5.5
Long-lived assets to be disposed of by sale | Estimated Fair Value | 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] |  |  |
Long-lived assets to be disposed of by sale | $ 5.0 |  | $ 5.5

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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. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 22 -URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
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