Segment Information - Total Asset Information For Segments (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,711.7		$ 2,359.4
Capital expenditures	125.5	$ 89.1
Racing Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	495.4		483.0
Capital expenditures	53.6	47.8
Casino Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	803.2		679.6
Capital expenditures	9.2	26.0
TwinSpires [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	225.8		215.9
Capital expenditures	7.1	7.3
Big Fish Games [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	0.0		892.5
Capital expenditures	0.0	5.6
Other Investments Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	84.9		15.2
Capital expenditures	53.8	1.3
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	102.4		$ 73.2
Capital expenditures	$ 1.8	$ 1.1