Segment Information - Total Asset Information For Segments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,696.6		$ 2,359.4
Capital expenditures	72.2	$ 64.0
Racing Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	496.4		483.0
Capital expenditures	43.0	38.4
Casino Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	671.9		679.6
Capital expenditures	5.9	15.6
TwinSpires [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	222.0		215.9
Capital expenditures	4.7	5.2
Big Fish Games [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	0.0		892.5
Capital expenditures	0.0	3.5
Other Investments Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	53.5		15.2
Capital expenditures	17.6	0.7
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	252.8		$ 73.2
Capital expenditures	$ 1.0	$ 0.6