Segment Information - Total Asset Information For Segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 2,478.5		$ 1,725.2
Capital expenditures	28.1	$ 34.0
Operating Segments | Total Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,208.9		1,459.5
Capital expenditures	23.6	32.5
Operating Segments | Churchill Downs
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	367.7		359.6
Capital expenditures	9.6	26.2
Operating Segments | Online Wagering
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	237.4		222.8
Capital expenditures	11.5	2.3
Operating Segments | Gaming
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,603.8		877.1
Capital expenditures	2.5	4.0
Segment Reconciling Items | All Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	269.6		$ 265.7
Capital expenditures	$ 4.5	$ 1.5