Other Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization of definite-lived intangible assets		$ 6.8	$ 9.4	$ 10.5
Additional payments not included in future estimated amortization expense	$ 2.3	2.3
Calder
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired		2.3	$ 2.3
Illinois Horseracing Equity Trust | Racing
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	3.3
BetAmerica Corporation | Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		4.7
BetAmerica Corporation | Other
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		$ 3.4
Bluff Media | TwinSpires
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets (Excluding Goodwill)	4.7
Bluff Media | TwinSpires | Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived	0.2
Bluff Media | Trademarks | TwinSpires
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	$ 4.5