Segment Information - Total Asset Information For Segments (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 3,263.0		$ 2,551.0
Capital expenditures	210.1	$ 91.0
Operating Segments | Total Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,616.6		1,641.9
Capital expenditures	52.0	62.7
Operating Segments | Churchill Downs
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	394.2		370.3
Capital expenditures	37.3	24.7
Operating Segments | Online Wagering
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	253.5		241.5
Capital expenditures	9.6	7.3
Operating Segments | Gaming
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	968.9		1,030.1
Capital expenditures	5.1	30.7
Segment Reconciling Items | All Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,646.4		$ 909.1
Capital expenditures	$ 158.1	$ 28.3