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Business Combinations, Goodwill and Intangible Assets - Schedule of Goodwill (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2020 | Dec. 31, 2019
Goodwill [Roll Forward] |  |  |
Gross carrying value | $ 62.4 | $ 37.2 | $ 62.4
Accumulated impairment loss: |  |  |
Beginning balance |  | (18.4) | (18.4)
Impairment loss | (25.2) | 0.0 | (25.2)
Ending balance | (43.6) | (18.4) | (43.6)
Goodwill | $ 18.8 | $ 18.8 | $ 18.8

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