Segment Information - Schedule of Total Assets and Capital Expenditures by Operating Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 2,359.4	$ 2,254.4
Capital expenditures	116.9	54.7	$ 43.5
Racing
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	483.0	454.6
Capital expenditures	57.8	26.1	12.3
Casino
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	679.6	628.7
Capital expenditures	37.5	13.9	18.8
TwinSpires
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	215.9	209.9
Capital expenditures	9.0	7.0	4.3
Other Investments
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	15.2	11.1
Capital expenditures	3.4	1.0	0.8
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	73.2	56.3
Capital expenditures	1.3	1.2	0.9
Discontinued Operations, Held-for-sale | Big Fish Games
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	892.5	893.8
Capital expenditures	$ 7.9	$ 5.5	$ 6.4