Goodwill And Indefinite-Lived Intangible Assets Impairment Test Goodwill (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill	$ 317.6	$ 317.6
Goodwill, Acquired During Period	0.0
Racing Segment [Member]
Goodwill [Line Items]
Goodwill	51.7	51.7
Goodwill, Acquired During Period	0.0
Casino Segment [Member]
Goodwill [Line Items]
Goodwill	117.7	117.7
Goodwill, Acquired During Period	0.0
TwinSpires [Member]
Goodwill [Line Items]
Goodwill	148.2	$ 148.2
Goodwill, Acquired During Period	$ 0.0