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Goodwill and Core Deposit Intangibles - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2022 | Dec. 31, 2023 | Dec. 31, 2021
Finite-lived Intangible Assets [Roll Forward] |  |  |
Finite-Lived Intangible Assets, Gross | $ 177.5 |  | $ 106.0
Finite-lived intangible assets acquired | 72.9 |  |
Finite-Lived Intangible Assets, Period Increase (Decrease) | (1.4) |  |
Finite-Lived Intangible Assets, Accumulated Amortization | (80.5) | $ (96.1) |
Finite-Lived Intangible Assets, Net | 97.0 | 81.4 |
Core Deposits Intangibles |  |  |
Finite-lived Intangible Assets [Roll Forward] |  |  |
Finite-Lived Intangible Assets, Gross | 154.7 |  | 106.0
Finite-lived intangible assets acquired | 50.1 |  |
Finite-Lived Intangible Assets, Period Increase (Decrease) | (1.4) |  |
Finite-Lived Intangible Assets, Accumulated Amortization | (78.8) | (92.5) |
Finite-Lived Intangible Assets, Net | 75.9 | 62.2 |
OCRI |  |  |
Finite-lived Intangible Assets [Roll Forward] |  |  |
Finite-Lived Intangible Assets, Gross | 22.8 |  | $ 0.0
Finite-lived intangible assets acquired | 22.8 |  |
Finite-Lived Intangible Assets, Period Increase (Decrease) | 0.0 |  |
Finite-Lived Intangible Assets, Accumulated Amortization | (1.7) | (3.6) |
Finite-Lived Intangible Assets, Net | $ 21.1 | $ 19.2 |

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