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Goodwill and Other Intangible Assets - Schedule of Goodwill and Other Intangible Assets Rollforward (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2022 | Sep. 30, 2021
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |
Goodwill, beginning balance |  |  | $ 142.3 |
Amortization of other intangible assets | $ (1.4) | $ (2.0) | (3.4) | $ (3.1)
Goodwill, ending balance | 175.5 |  | 175.5 |
Goodwill |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |
Goodwill, beginning balance | 201.8 | 151.5 | 142.3 | 19.2
Acquisition of businesses |  |  | 59.5 | 15.8
Attribution of acquisition date fair value estimates between goodwill and other intangible assets | (22.9) | (9.3) | (22.9) | (9.3)
Measurement period adjustments | (3.4) | (0.4) | (3.4) | (0.7)
Amortization of other intangible assets | 0.0 | 0.0 | 0.0 | 0.0
Goodwill, ending balance | 175.5 | 141.8 | 175.5 | 141.8
Goodwill | Ark |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |
Goodwill acquired |  |  | 0.0 | 116.8
Other |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |
Other intangible assets (excluding goodwill), beginning balance | 196.2 | 201.1 | 198.2 | 26.4
Acquisition of businesses |  |  | 0.0 | 0.0
Attribution of acquisition date fair value estimates between goodwill and other intangible assets | 22.9 | 9.3 | 22.9 | 9.3
Measurement period adjustments | 0.0 | 0.0 |  | 0.1
Amortization of other intangible assets | (1.4) | (2.0) | (3.4) | (3.1)
Other intangible assets (excluding goodwill), ending balance | 217.7 | 208.4 | 217.7 | 208.4
Other | Ark |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |
Intangible assets acquired |  |  | 0.0 | 175.7
Total Goodwill and Other Intangible Assets |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |
Other intangible assets, gross (including goodwill), beginning balance | 398.0 | 352.6 | 340.5 | 45.6
Acquisition of businesses |  |  | 59.5 | 15.8
Attribution of acquisition date fair value estimates between goodwill and other intangible assets | 0.0 | 0.0 | 0.0 | 0.0
Measurement period adjustments | (3.4) | (0.4) | (3.4) | (0.6)
Amortization of other intangible assets | (1.4) | (2.0) | (3.4) | (3.1)
Other intangible assets, gross (including goodwill), ending balance | $ 393.2 | $ 350.2 | 393.2 | 350.2
Total Goodwill and Other Intangible Assets | Ark |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |
Goodwill and other intangible assets acquired |  |  | $ 0.0 | $ 292.5

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