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Derivatives and Hedging Activities - Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022 | Dec. 31, 2022
Derivative [Line Items] |  |  |  |  |
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net | $ 12.2 |  | $ 12.2 |  |
Derivative Instruments and Hedges, Assets | 192.6 |  | 192.6 |  | $ 191.9
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease) | 7.4 |  | 7.4 |  | 8.1
Financial Instruments | 0.0 |  | 0.0 |  | 0.0
Derivative Asset, Notional Amount | 1,659.1 |  | 1,659.1 |  | 2,290.7
Derivative Asset, Estimated Fair Value | 40.2 |  | 40.2 |  | 45.2
Derivative Liability, Notional Amount | 2,914.5 |  | 2,914.5 |  | 2,449.0
Derivative Liabilities, Estimated Fair Value | 163.1 |  | 163.1 |  | 159.6
Collateral Pledged |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Fair Value, Net | 0.0 |  | 0.0 |  |
Financial Instruments | 0.0 |  | 0.0 |  |
Not Designated as Hedging Instrument |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Amount of net fee income recognized in other non-interest income | 0.5 | $ 1.1 | 6.5 | $ 3.1 |
Amount of net gains recognized in mortgage banking revenues | 0.2 | 1.0 | 0.2 | 1.5 |
Interest Rate Swap |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative Instruments and Hedges, Assets | 850.0 |  | 850.0 |  |
Financial Instruments | 0.0 |  | 0.0 |  | 0.0
Interest Rate Swap | Designated as Hedging Instrument [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative Asset, Notional Amount | 0.0 |  | 0.0 |  | 550.0
Derivative Asset, Estimated Fair Value | 0.0 |  | 0.0 |  | 3.5
Derivative Liability, Notional Amount | 850.0 |  | 850.0 |  | 300.0
Derivative Liabilities, Estimated Fair Value | 7.7 |  | 7.7 |  | 0.3
Interest Rate Swap | Not Designated as Hedging Instrument |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative Asset, Notional Amount | 1,645.7 |  | 1,645.7 |  | 1,728.1
Derivative Asset, Estimated Fair Value | 40.2 |  | 40.2 |  | 41.6
Derivative Liability, Notional Amount | 1,645.7 |  | 1,645.7 |  | 1,728.1
Derivative Liabilities, Estimated Fair Value | 148.3 |  | 148.3 |  | 153.9
Risk Participation Agreements | Not Designated as Hedging Instrument |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative Liability, Notional Amount | 103.7 |  | 103.7 |  | 106.1
Derivative Liabilities, Estimated Fair Value | 0.0 |  | 0.0 |  | 0.0
Forward Contracts | Not Designated as Hedging Instrument |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Fair Value, Net | 0.0 |  | 0.0 |  | 0.1
Derivative Asset, Notional Amount | 13.4 |  | 13.4 |  | 12.6
Interest Rate Lock Commitments |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Financial Instruments | 0.0 |  | 0.0 |  |
Interest Rate Lock Commitments | Not Designated as Hedging Instrument |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative Liability, Notional Amount | 15.1 |  | 15.1 |  | 14.8
Derivative Liabilities, Estimated Fair Value | 0.1 |  | 0.1 |  | 0.0
Interest Rate Collars |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative Instruments and Hedges, Assets | 300.0 |  | 300.0 |  |
Interest Rate Collars | Designated as Hedging Instrument [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative Liability, Notional Amount | 300.0 |  | 300.0 |  | 300.0
Derivative Liabilities, Estimated Fair Value | 7.0 |  | 7.0 |  | $ 5.4
Cash Flow Hedging [Member] | Interest Rate Swap | Designated as Hedging Instrument [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax | $ (14.7) | $ 0.0 | $ (14.7) | $ 0.0 |

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