Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Goodwill - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Oct. 09, 2019	Mar. 31, 2019	Jan. 11, 2019	Dec. 31, 2017
Indefinite-lived Intangible Assets [Line Items]
Goodwill	$ 367.1	$ 338.0				$ 317.6
Additions	29.1	20.4
Churchill Downs
Indefinite-lived Intangible Assets [Line Items]
Goodwill				$ 51.7
Churchill Downs Reporting Unit
Indefinite-lived Intangible Assets [Line Items]
Goodwill				49.7
Gaming
Indefinite-lived Intangible Assets [Line Items]
Goodwill				1.0
Arlington Reporting Unit
Indefinite-lived Intangible Assets [Line Items]
Goodwill				$ 1.0
Presque Isle
Indefinite-lived Intangible Assets [Line Items]
Goodwill					$ 26.1
Turfway Park
Indefinite-lived Intangible Assets [Line Items]
Goodwill			$ 3.0
Gaming \| Presque Isle
Indefinite-lived Intangible Assets [Line Items]
Additions	26.1
Gaming \| Turfway Park
Indefinite-lived Intangible Assets [Line Items]
Additions	$ 3.0
Gaming \| Ocean Downs
Indefinite-lived Intangible Assets [Line Items]
Additions		$ 20.4