Segment Information - Schedule of Net Revenue from External Customers (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 324.3	$ 252.9
Disclosure of complimentary revenue	3.7	7.6
Revenue from Related Parties	0.0	0.0
Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	64.7	29.1
TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	100.1	69.4
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	154.0	147.4
Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	324.3	252.9
Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	63.2	28.1
Revenue from Related Parties	1.5	1.0
Operating Segments | Live and Historical Racing | Churchill Downs Racetrack
Segment Reporting Information [Line Items]
Net revenue from external customers	2.0	1.9
Operating Segments | Live and Historical Racing | Derby City Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	32.9	21.6
Operating Segments | Live and Historical Racing | Oak Grove
Segment Reporting Information [Line Items]
Net revenue from external customers	19.4	0.0
Operating Segments | Live and Historical Racing | Turfway Park
Segment Reporting Information [Line Items]
Net revenue from external customers	4.5	4.6
Operating Segments | Live and Historical Racing | Newport
Segment Reporting Information [Line Items]
Net revenue from external customers	4.4	0.0
Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	99.7	69.1
Revenue from Related Parties	0.4	0.3
Operating Segments | TwinSpires | Horse Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	92.7	66.6
Operating Segments | TwinSpires | Sports and Casino
Segment Reporting Information [Line Items]
Net revenue from external customers	7.0	2.5
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	152.0	145.9
Revenue from Related Parties	2.0	1.5
Operating Segments | Gaming | Fair Grounds and VSI
Segment Reporting Information [Line Items]
Net revenue from external customers	38.3	31.6
Operating Segments | Gaming | Presque Isle
Segment Reporting Information [Line Items]
Net revenue from external customers	23.8	27.0
Operating Segments | Gaming | Calder
Segment Reporting Information [Line Items]
Net revenue from external customers	20.9	21.8
Operating Segments | Gaming | Oxford
Segment Reporting Information [Line Items]
Net revenue from external customers	15.7	20.1
Operating Segments | Gaming | Ocean Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	20.0	14.8
Operating Segments | Gaming | Riverwalk
Segment Reporting Information [Line Items]
Net revenue from external customers	14.4	12.0
Operating Segments | Gaming | Harlow’s
Segment Reporting Information [Line Items]
Net revenue from external customers	14.0	11.3
Operating Segments | Gaming | Lady Luck Nemacolin
Segment Reporting Information [Line Items]
Net revenue from external customers	4.9	7.3
Segment Reconciling Items
Segment Reporting Information [Line Items]
Net revenue from external customers	9.4	9.8
Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Revenue from Related Parties	2.7	2.4
Eliminations
Segment Reporting Information [Line Items]
Revenue from Related Parties	(6.6)	(5.2)
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	152.0	145.9
Other
Segment Reporting Information [Line Items]
Net revenue from external customers	9.4	9.8
External Customer
Segment Reporting Information [Line Items]
Net revenue from external customers	324.3	252.9
External Customer | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	314.9	243.1
External Customer | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	63.2	28.1
External Customer | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	99.7	69.1
External Customer | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	152.0	145.9
External Customer | Segment Reconciling Items
Segment Reporting Information [Line Items]
Net revenue from external customers	9.4	9.8
External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenue from external customers	111.9	84.7
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	106.8	79.0
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	5.9	5.2
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	89.2	63.9
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	11.7	9.9
External Customer | Pari-mutuel, live and simulcast racing | Segment Reconciling Items
Segment Reporting Information [Line Items]
Net revenue from external customers	5.1	5.7
External Customer | Pari-mutuel, historical racing
Segment Reporting Information [Line Items]
Net revenue from external customers	52.9	20.4
External Customer | Pari-mutuel, historical racing | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	52.9	20.4
External Customer | Pari-mutuel, historical racing | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	52.9	20.4
External Customer | Pari-mutuel, historical racing | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
External Customer | Pari-mutuel, historical racing | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
External Customer | Pari-mutuel, historical racing | Segment Reconciling Items
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
External Customer | Racing event-related services
Segment Reporting Information [Line Items]
Net revenue from external customers	0.7	1.4
External Customer | Racing event-related services | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	0.7	1.3
External Customer | Racing event-related services | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
External Customer | Racing event-related services | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
External Customer | Racing event-related services | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	0.7	1.3
External Customer | Racing event-related services | Segment Reconciling Items
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.1
External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	139.5	122.3
External Customer | Gaming | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	139.5	122.3
External Customer | Gaming | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
External Customer | Gaming | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	7.0	2.5
External Customer | Gaming | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	132.5	119.8
External Customer | Gaming | Segment Reconciling Items
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
External Customer | Other
Segment Reporting Information [Line Items]
Net revenue from external customers	19.3	24.1
External Customer | Other | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	15.0	20.1
External Customer | Other | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	4.4	2.5
External Customer | Other | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	3.5	2.7
External Customer | Other | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	7.1	14.9
External Customer | Other | Segment Reconciling Items
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 4.3	$ 4.0