Segment Information - Total Asset Information For Segments (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 2,327.4		$ 2,254.4
Capital expenditures	89.1	$ 44.1
Racing Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	463.7		454.6
Capital expenditures	47.8	23.4
Casino Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	675.1		628.7
Capital expenditures	26.0	9.7
TwinSpires [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	213.0		209.9
Capital expenditures	7.3	5.4
Big Fish Games [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	902.8		893.8
Capital expenditures	5.6	3.6
Other Investments Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	11.9		11.1
Capital expenditures	1.3	0.8
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	60.9		$ 56.3
Capital expenditures	$ 1.1	$ 1.2