Segment Information - Total Asset Information For Segments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 3,216.0		$ 2,551.0
Capital expenditures	131.3	$ 58.8
Operating Segments | Total Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,590.8		1,641.9
Capital expenditures	38.8	55.0
Operating Segments | Churchill Downs
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	395.2		370.3
Capital expenditures	28.2	21.9
Operating Segments | Online Wagering
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	250.1		241.5
Capital expenditures	6.1	4.9
Operating Segments | Gaming
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	945.5		1,030.1
Capital expenditures	4.5	28.2
Segment Reconciling Items | All Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,625.2		$ 909.1
Capital expenditures	$ 92.5	$ 3.8