Goodwill - Schedule of Goodwill (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Goodwill [Roll Forward]
Balance, beginning of period	$ 301.5
Additions	16.1
Balance, end of period	317.6
Racing
Goodwill [Roll Forward]
Balance, beginning of period	51.7
Additions	0.0
Balance, end of period	51.7
Casino
Goodwill [Roll Forward]
Balance, beginning of period	117.7
Additions	0.0
Balance, end of period	117.7
TwinSpires
Goodwill [Roll Forward]
Balance, beginning of period	132.1
Additions	16.1
Balance, end of period	$ 148.2