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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 | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019 | Dec. 31, 2019
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Goodwill, beginning balance |  |  | $ 394.7 |  |
Other intangible assets, impairments |  |  | (6.2) |  | $ (2.8)
Amortization of other intangible assets | $ 5.4 | $ 4.6 | 17.1 | $ 15.4 |
Goodwill, ending balance | 540.1 |  | 540.1 |  | 394.7
Renewal rights |  |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Payments to acquire intangible assets |  | 0.0 |  | 82.5 |
Goodwill |  |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Goodwill, beginning balance | 518.2 | 428.6 | 394.7 | 379.9 | 379.9
Deconsolidation of business |  |  | 0.0 | (18.3) |
Attribution of acquisition date fair value estimates between goodwill and other intangible assets | 0.0 | (2.2) | 0.0 | (29.0) |
Acquisitions of businesses | 14.9 | 0.0 | 140.0 | 93.8 |
Goodwill, foreign currency translation gain (loss) | 7.0 | (1.6) | 5.2 | (1.6) |
Measurement period adjustments |  |  | 0.2 | 0.0 |
Other intangible assets, impairments |  |  | 0.0 | 0.0 |
Goodwill, ending balance | 540.1 | 424.8 | 540.1 | 424.8 | 394.7
Goodwill | Renewal rights |  |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Payments to acquire intangible assets | 0.0 | 0.0 | 0.0 | 0.0 |
Other Intangible Assets |  |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Other intangible assets (excluding goodwill), beginning balance | 241.7 | 239.0 | 260.0 | 157.6 | 157.6
Deconsolidation of business |  |  | 0.0 | (23.5) |
Attribution of acquisition date fair value estimates between goodwill and other intangible assets | 0.0 | 2.2 | 0.0 | 29.0 |
Acquisitions of businesses | 0.0 | 0.0 | 0.0 | 0.0 |
Other intangible assets, foreign currency translation gain (loss) | (0.1) | (0.5) | (0.5) | 0.0 |
Measurement period adjustments |  |  | 0.0 | 5.9 |
Other intangible assets, impairments |  |  | (6.2) | 0.0 |
Amortization of other intangible assets |  |  | 17.1 | 15.4 |
Other intangible assets (excluding goodwill), ending balance | 236.2 | 236.1 | 236.2 | 236.1 | 260.0
Other Intangible Assets | Renewal rights |  |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Payments to acquire intangible assets | 0.0 | 0.0 | 0.0 | 82.5 |
Total Goodwill and Other Intangible Assets |  |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Other intangible assets, gross (including goodwill), beginning balance | 759.9 | 667.6 | 654.7 | 537.5 | 537.5
Deconsolidation of business |  |  | 0.0 | (41.8) |
Attribution of acquisition date fair value estimates between goodwill and other intangible assets | 0.0 | 0.0 | 0.0 | 0.0 |
Acquisitions of businesses | 14.9 | 0.0 | 140.0 | 93.8 |
Other intangible assets, foreign currency translation gain (loss) | 6.9 | (2.1) | 4.7 | (1.6) |
Measurement period adjustments |  |  | 0.2 | 5.9 |
Other intangible assets, impairments |  |  | (6.2) | 0.0 |
Amortization of other intangible assets | 5.4 | 4.6 | 17.1 | 15.4 |
Other intangible assets, gross (including goodwill), ending balance | 776.3 | $ 660.9 | 776.3 | $ 660.9 | $ 654.7
Total Goodwill and Other Intangible Assets | Renewal rights |  |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |
Payments to acquire intangible assets | $ 0.0 |  | $ 0.0 |  |

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