Segment Information - Total Asset Information For Segments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 2,588.5		$ 1,725.2
Capital expenditures	58.8	$ 72.4
Gaming
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,605.3		877.1
Operating Segments | Total Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,221.0		1,459.5
Capital expenditures	55.0	69.4
Operating Segments | Churchill Downs
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	371.4		359.6
Capital expenditures	21.9	56.1
Operating Segments | Online Wagering
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	244.3		222.8
Capital expenditures	4.9	4.7
Operating Segments | Gaming
Segment Reporting, Asset Reconciling Item [Line Items]
Capital expenditures	28.2	8.6
Segment Reconciling Items | All Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	367.5		$ 265.7
Capital expenditures	$ 3.8	$ 3.0