Segment Information - Total Asset Information For Segments (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 2,562.5		$ 1,725.2
Capital expenditures	91.0	$ 125.5
Gaming
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,606.8		877.1
Operating Segments | Total Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,213.8		1,459.5
Capital expenditures	62.7	120.9
Operating Segments | Churchill Downs
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	364.5		359.6
Capital expenditures	24.7	100.6
Operating Segments | Online Wagering
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	242.5		222.8
Capital expenditures	7.3	7.1
Operating Segments | Gaming
Segment Reporting, Asset Reconciling Item [Line Items]
Capital expenditures	30.7	13.2
Segment Reconciling Items | All Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	348.7		$ 265.7
Capital expenditures	$ 28.3	$ 4.6