Segment Information - Total Asset Information For Segments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 2,282.0		$ 2,254.4
Capital expenditures	64.0	$ 34.5
Racing Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	453.2		454.6
Capital expenditures	38.4	20.7
Casino Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	659.8		628.7
Capital expenditures	15.6	6.8
TwinSpires [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	207.5		209.9
Capital expenditures	5.2	3.7
Big Fish Games [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	890.9		893.8
Capital expenditures	3.5	2.2
Other Investments Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	10.1		11.1
Capital expenditures	0.7	0.5
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	60.5		$ 56.3
Capital expenditures	$ 0.6	$ 0.6