Goodwill - Schedule of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Balance, beginning of period	$ 338.0	$ 317.6
Additions	29.1	20.4
Balance, end of period	367.1	338.0
Churchill Downs
Goodwill [Roll Forward]
Balance, beginning of period	49.7	49.7
Additions	0.0	0.0
Balance, end of period	49.7	49.7
Online Wagering
Goodwill [Roll Forward]
Balance, beginning of period	148.2	148.2
Additions	0.0	0.0
Balance, end of period	148.2	148.2
Gaming
Goodwill [Roll Forward]
Balance, beginning of period	139.1	118.7
Additions	26.1	20.4
Balance, end of period	165.2	139.1
All Other
Goodwill [Roll Forward]
Balance, beginning of period	1.0	1.0
Additions	3.0	0.0
Balance, end of period	$ 4.0	$ 1.0