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Goodwill and Other Intangible Assets - Schedule of Goodwill and Other Intangible Assets Rollforward (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2022 | Jun. 30, 2021 | Jun. 30, 2022 | Jun. 30, 2021
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |
Goodwill, beginning balance |  |  | $ 142.3 |
Amortization of other intangible assets | $ (1.0) | $ (0.5) | (2.0) | $ (1.1)
Goodwill, ending balance | 201.8 |  | 201.8 |
Goodwill |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |
Goodwill, beginning balance | 142.3 | 135.7 | 142.3 | 19.2
Acquisition of businesses | 59.5 | 15.8 | 59.5 | 15.8
Measurement period adjustments |  |  | 0.0 | (0.3)
Amortization of other intangible assets | 0.0 | 0.0 | 0.0 | 0.0
Goodwill, ending balance | 201.8 | 151.5 | 201.8 | 151.5
Goodwill | Other |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |
Measurement period adjustments |  |  |  | 0.2
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 | 197.2 | 201.6 | 198.2 | 26.4
Acquisition of businesses | 0.0 | 0.0 | 0.0 | 0.0
Measurement period adjustments |  |  | 0.0 | 0.1
Amortization of other intangible assets | (1.0) | (0.5) | (2.0) | (1.1)
Other intangible assets (excluding goodwill), ending balance | 196.2 | 201.1 | 196.2 | 201.1
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 | 339.5 | 337.3 | 340.5 | 45.6
Acquisition of businesses | 59.5 | 15.8 | 59.5 | 15.8
Measurement period adjustments |  |  | 0.0 | (0.2)
Amortization of other intangible assets | (1.0) | (0.5) | (2.0) | (1.1)
Other intangible assets, gross (including goodwill), ending balance | $ 398.0 | $ 352.6 | 398.0 | 352.6
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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