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GOODWILL (Goodwill by Segment) (Details) - USD ($) $ in Millions |  | 1 Months Ended | 12 Months Ended
--- | --- | --- | ---
May 24, 2021 | Dec. 31, 2023 | Apr. 30, 2022 | Dec. 31, 2023 | Dec. 31, 2022
Goodwill [Roll Forward] |  |  |  |  |
Goodwill, beginning balance |  |  |  | $ 2,314.8 | $ 2,321.0
Acquisitions, including measurement period adjustments |  |  |  | 62.8 | 10.5
Effect of foreign currency translation |  |  |  | 8.6 | (16.7)
Goodwill, ending balance |  | $ 2,386.2 |  | 2,386.2 | 2,314.8
Homes.com |  |  |  |  |
Goodwill [Roll Forward] |  |  |  |  |
Goodwill, ending balance | $ 91.9 |  |  |  |
Business Immo |  |  |  |  |
Goodwill [Roll Forward] |  |  |  |  |
Goodwill acquired |  |  | $ 7.1 |  |
North America |  |  |  |  |
Goodwill [Roll Forward] |  |  |  |  |
Goodwill, beginning balance |  |  |  | 2,149.2 | 2,145.8
Acquisitions, including measurement period adjustments |  |  |  | 0.0 | 3.4
Effect of foreign currency translation |  |  |  | 0.0 | 0.0
Goodwill, ending balance |  | 2,149.2 |  | 2,149.2 | 2,149.2
North America | Homes.com |  |  |  |  |
Goodwill [Roll Forward] |  |  |  |  |
Goodwill acquired | $ 91.9 |  |  |  |
Goodwill measuring period adjustment |  |  |  |  | 3.4
North America | OnTheMarket |  |  |  |  |
Goodwill [Roll Forward] |  |  |  |  |
Goodwill acquired |  | 62.8 |  |  |
International |  |  |  |  |
Goodwill [Roll Forward] |  |  |  |  |
Goodwill, beginning balance |  |  |  | 165.6 | 175.2
Acquisitions, including measurement period adjustments |  |  |  | 62.8 | 7.1
Effect of foreign currency translation |  |  |  | 8.6 | (16.7)
Goodwill, ending balance |  | $ 237.0 |  | 237.0 | 165.6
International | Business Immo |  |  |  |  |
Goodwill [Roll Forward] |  |  |  |  |
Goodwill acquired |  |  |  |  | $ 7.1
International | OnTheMarket |  |  |  |  |
Goodwill [Roll Forward] |  |  |  |  |
Goodwill acquired |  |  |  | $ 62.8 |

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