| **Stock-based Compensation Plans - Additional Information (Details) $ in Millions** | 3 Months Ended | 9 Months Ended |
|-------------------------------------------------------------------------------------|----------------|----------------|
||
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**  |           |           |   |   |
| Stock-based compensation                                                            |           |           | $ 23.2 | $ 24.8 |
| Number of performance criteria | performance_criteria                               |           |           | 2 |   |
| PSUs | Churchill Downs Incorporated 2016 Omnibus Stock Incentive Plan               |           |           |   |   |
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**  |           |           |   |   |
| Award vesting period (in years)                                                     |           |           | 3 years |   |
| Number of performance conditions | performance_condition                            |           |           | 2 |   |
| Continuing Operations                                                               |           |           |   |   |
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**  |           |           |   |   |
| Stock-based compensation                                                            | $ 7.1          | $ 8.1          | $ 23.2 | $ 24.8 |

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| - Definition
Amount of noncash expense for share-based payment arrangement.
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| - Definition
Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.
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| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
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