Segment Information - Summary of Assets (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 2,970.6	$ 2,686.4
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,898.2	1,870.6
Operating Segments | Live and Historical Racing
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	653.6	664.1
Operating Segments | TwinSpires
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	280.5	257.2
Operating Segments | Gaming
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	964.1	949.3
All Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,072.4	$ 815.8