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Goodwill and Other Intangible Assets - Goodwill Rollforward (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015 | Jun. 30, 2016 | Dec. 31, 2015 | Jun. 30, 2015 | Dec. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |  |
Goodwill |  |  |  |  | $ 24.1 | $ 24.1 | $ 24.1 | $ 23.8
Intangible Assets, Net (Excluding Goodwill) |  |  |  |  | 29.2 | 31.3 | 36.4 | 38.7
Goodwill and other intangible assets | $ 59.3 | $ 58.0 | $ 59.3 | $ 58.0 | 53.3 | 55.4 | 60.5 | 62.5
Other Intangible Assets, Net | 9.0 |  | 9.0 |  |  |  |  |
Disposal Group, Including Discontinued Operation, Intangible Assets |  | 0.5 |  | 0.5 | $ 0.0 | 0.4 | 0.6 | 0.8
Goodwill, Acquired During Period |  |  |  | 0.3 |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill |  |  | 9.0 | 2.8 |  |  |  |
Finite-lived Intangible Assets Acquired |  |  | 3.9 |  |  |  |  |
Amortization of Intangible Assets | (3.0) | (2.6) | (9.4) | (7.9) |  |  |  |
WTM entities except Buzzmove [Member] |  |  |  |  |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |  |
Goodwill | 24.1 | 24.1 | 24.1 | 24.1 |  |  |  |
Intangible Assets, Net (Excluding Goodwill) | 26.2 | 33.9 | 26.2 | 33.9 |  |  |  |
Goodwill and other intangible assets | 50.3 | 58.0 | 50.3 | 58.0 |  |  |  |
Intangible Asset and Goodwill [Member] |  |  |  |  |  |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |  |
Disposal Group, Including Discontinued Operation, Intangible Assets |  | 0.5 |  | 0.5 |  | $ 0.4 | $ 0.6 | $ 0.8
Acquisition of goodwill and intangible assets |  |  |  | 3.1 |  |  |  |
Finite-lived Intangible Assets Acquired |  |  | 3.9 |  |  |  |  |
Amortization of Intangible Assets | $ (3.0) | $ (2.6) | $ (9.4) | $ (7.9) |  |  |  |

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