| **Segment Information - Summary of Assets (Details) - USD ($) $ in Millions** | 3 Months Ended | 6 Months Ended |           |
|-------------------------------------------------------------------------------|----------------|----------------|-----------|
||
| **Segment Reporting, Asset Reconciling Item [Line Items]**                    |           |           |      |   |   |
| Total assets                                                                  | $ 4,619.6      |           | $ 4,619.6 |   | $ 2,981.6 |
| Net revenue                                                                   | 582.5          | $ 515.1        | 946.6     | $ 839.4 |   |
| Live and Historical Racing                                                    |           |           |      |   |   |
| **Segment Reporting, Asset Reconciling Item [Line Items]**                    |           |           |      |   |   |
| Net revenue                                                                   | 275.9          | 190.5          | 363.1     | 255.2 |   |
| TwinSpires                                                                    |           |           |      |   |   |
| **Segment Reporting, Asset Reconciling Item [Line Items]**                    |           |           |      |   |   |
| Net revenue                                                                   | 138.5          | 142.6          | 239.9     | 247.6 |   |
| Gaming                                                                        |           |           |      |   |   |
| **Segment Reporting, Asset Reconciling Item [Line Items]**                    |           |           |      |   |   |
| Net revenue                                                                   | 184.5          | 186.0          | 363.7     | 340.0 |   |
| Operating Segments                                                            |           |           |      |   |   |
| **Segment Reporting, Asset Reconciling Item [Line Items]**                    |           |           |      |   |   |
| Total assets                                                                  | 2,395.6        |           | 2,395.6   |   | 1,975.6 |
| Net revenue                                                                   | 582.5          | 515.1          | 946.6     | 839.4 |   |
| Operating Segments | Live and Historical Racing                               |           |           |      |   |   |
| **Segment Reporting, Asset Reconciling Item [Line Items]**                    |           |           |      |   |   |
| Total assets                                                                  | 810.8          |           | 810.8     |   | 682.7 |
| Net revenue                                                                   | 260.9          | 175.9          | 346.9     | 239.1 |   |
| Operating Segments | TwinSpires                                               |           |           |      |   |   |
| **Segment Reporting, Asset Reconciling Item [Line Items]**                    |           |           |      |   |   |
| Total assets                                                                  | 296.1          |           | 296.1     |   | 289.6 |
| Net revenue                                                                   | 136.8          | 140.8          | 237.1     | 244.3 |   |
| Operating Segments | Gaming                                                   |           |           |      |   |   |
| **Segment Reporting, Asset Reconciling Item [Line Items]**                    |           |           |      |   |   |
| Total assets                                                                  | 1,288.7        |           | 1,288.7   |   | 1,003.3 |
| Net revenue                                                                   | 184.3          | 186.0          | 361.6     | 338.0 |   |
| All Other                                                                     |           |           |      |   |   |
| **Segment Reporting, Asset Reconciling Item [Line Items]**                    |           |           |      |   |   |
| Total assets                                                                  | 2,224.0        |           | 2,224.0   |   | $ 1,006.0 |
| Net revenue                                                                   | $ 0.5          | $ 12.4         | $ 1.0     | $ 18.0 |   |

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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------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| - Definition
Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.
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| - Definition
Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).
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