Segment Information - Net Revenue From External Customers and Intercompany Revenue From Each Operating Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Net revenue	$ 768.5	$ 582.5	$ 1,328.0	$ 946.6
Live and Historical
Segment Reporting Information [Line Items]
Net revenue	408.0	275.9	623.8	363.1
TwinSpires
Segment Reporting Information [Line Items]
Net revenue	139.1	138.5	235.5	239.9
Gaming
Segment Reporting Information [Line Items]
Net revenue	247.9	184.5	499.5	363.7
External Customer
Segment Reporting Information [Line Items]
Net revenue	768.5	582.5	1,328.0	946.6
Operating Segments | Live and Historical
Segment Reporting Information [Line Items]
Net revenue	385.0	260.9	599.4	346.9
Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue	137.4	136.8	232.2	237.1
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue	245.9	184.3	495.9	361.6
Operating Segments | External Customer
Segment Reporting Information [Line Items]
Net revenue	768.3	582.0	1,327.5	945.6
Operating Segments | External Customer | Live and Historical
Segment Reporting Information [Line Items]
Net revenue	385.0	260.9	599.4	346.9
Operating Segments | External Customer | TwinSpires
Segment Reporting Information [Line Items]
Net revenue	137.4	136.8	232.2	237.1
Operating Segments | External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenue	245.9	184.3	495.9	361.6
All Other
Segment Reporting Information [Line Items]
Net revenue	0.2	0.5	0.5	1.0
All Other | External Customer
Segment Reporting Information [Line Items]
Net revenue	$ 0.2	$ 0.5	$ 0.5	$ 1.0