Segment Information - Schedule of Net Revenue from External Customers (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 393.0	$ 337.8	$ 1,232.4	$ 775.8
Intercompany net revenue	0.0	0.0	0.0	0.0
Disclosure of complimentary revenue	6.1	2.1	15.0	10.5
Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	81.5	71.1	336.7	130.5
TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	102.2	127.6	338.2	318.7
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	185.6	133.7	525.6	318.4
Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	393.0	337.8	1,232.4	775.8
Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	79.7	63.8	318.8	115.2
Intercompany net revenue	1.8	7.3	17.9	15.3
Operating Segments | Live and Historical Racing | Churchill Downs Racetrack
Segment Reporting Information [Line Items]
Net revenue from external customers	7.4	34.9	114.6	52.4
Operating Segments | Live and Historical Racing | Derby City Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	40.2	25.9	113.0	55.2
Operating Segments | Live and Historical Racing | Oak Grove
Segment Reporting Information [Line Items]
Net revenue from external customers	27.1	2.4	72.1	2.4
Operating Segments | Live and Historical Racing | Turfway Park
Segment Reporting Information [Line Items]
Net revenue from external customers	0.7	0.6	5.8	5.2
Operating Segments | Live and Historical Racing | Newport
Segment Reporting Information [Line Items]
Net revenue from external customers	4.3	0.0	13.3	0.0
Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	101.8	127.1	337.1	317.5
Intercompany net revenue	0.4	0.5	1.1	1.2
Operating Segments | TwinSpires | Horse Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	93.1	124.0	313.0	310.5
Operating Segments | TwinSpires | Sports and Casino
Segment Reporting Information [Line Items]
Net revenue from external customers	8.7	3.1	24.1	7.0
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	185.3	133.5	523.3	316.7
Intercompany net revenue	0.3	0.2	2.3	1.7
Operating Segments | Gaming | Fair Grounds and VSI
Segment Reporting Information [Line Items]
Net revenue from external customers	24.8	27.9	98.2	70.6
Operating Segments | Gaming | Presque Isle
Segment Reporting Information [Line Items]
Net revenue from external customers	35.9	27.5	90.2	56.4
Operating Segments | Gaming | Ocean Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	31.7	24.3	78.7	42.2
Operating Segments | Gaming | Calder
Segment Reporting Information [Line Items]
Net revenue from external customers	25.9	6.5	74.2	34.0
Operating Segments | Gaming | Oxford
Segment Reporting Information [Line Items]
Net revenue from external customers	31.8	12.2	72.1	32.4
Operating Segments | Gaming | Riverwalk
Segment Reporting Information [Line Items]
Net revenue from external customers	14.5	15.2	47.3	34.6
Operating Segments | Gaming | Harlow’s
Segment Reporting Information [Line Items]
Net revenue from external customers	13.3	12.7	43.9	29.7
Operating Segments | Gaming | Lady Luck Nemacolin
Segment Reporting Information [Line Items]
Net revenue from external customers	7.4	7.2	18.7	16.8
All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	26.2	13.4	53.2	26.4
Intercompany net revenue	3.6	3.8	10.2	9.0
Eliminations
Segment Reporting Information [Line Items]
Intercompany net revenue	(6.1)	(11.8)	(31.5)	(27.2)
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	185.3	133.5	523.3	316.7
Other
Segment Reporting Information [Line Items]
Net revenue from external customers	26.2	13.4	53.2	26.4
External Customer
Segment Reporting Information [Line Items]
Net revenue from external customers	393.0	337.8	1,232.4	775.8
External Customer | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	366.8	324.4	1,179.2	749.4
External Customer | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	79.7	63.8	318.8	115.2
External Customer | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	101.8	127.1	337.1	317.5
External Customer | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	185.3	133.5	523.3	316.7
External Customer | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	26.2	13.4	53.2	26.4
External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenue from external customers	112.3	146.9	399.3	364.6
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	99.7	138.5	372.1	349.7
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	5.4	14.9	50.9	35.0
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	89.4	119.0	300.2	298.5
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	4.9	4.6	21.0	16.2
External Customer | Pari-mutuel, live and simulcast racing | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	12.6	8.4	27.2	14.9
External Customer | Pari-mutuel, historical racing
Segment Reporting Information [Line Items]
Net revenue from external customers	66.2	27.1	184.0	54.8
External Customer | Pari-mutuel, historical racing | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	66.2	27.1	184.0	54.8
External Customer | Pari-mutuel, historical racing | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	66.2	27.1	184.0	54.8
External Customer | Pari-mutuel, historical racing | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0	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	0.0	0.0
External Customer | Pari-mutuel, historical racing | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0	0.0	0.0
External Customer | Racing event-related services
Segment Reporting Information [Line Items]
Net revenue from external customers	6.9	20.0	73.2	22.6
External Customer | Racing event-related services | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	1.9	19.8	66.3	22.3
External Customer | Racing event-related services | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	1.8	19.1	65.3	19.6
External Customer | Racing event-related services | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0	0.0	0.0
External Customer | Racing event-related services | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	0.1	0.7	1.0	2.7
External Customer | Racing event-related services | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	5.0	0.2	6.9	0.3
External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	175.3	125.4	493.4	282.5
External Customer | Gaming | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	175.3	125.4	493.4	282.5
External Customer | Gaming | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0	0.0	0.0
External Customer | Gaming | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	8.7	3.1	24.1	7.0
External Customer | Gaming | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	166.6	122.3	469.3	275.5
External Customer | Gaming | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0	0.0	0.0
External Customer | Other
Segment Reporting Information [Line Items]
Net revenue from external customers	32.3	18.4	82.5	51.3
External Customer | Other | Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	23.7	13.6	63.4	40.1
External Customer | Other | Operating Segments | Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue from external customers	6.3	2.7	18.6	5.8
External Customer | Other | Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenue from external customers	3.7	5.0	12.8	12.0
External Customer | Other | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	13.7	5.9	32.0	22.3
External Customer | Other | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 8.6	$ 4.8	$ 19.1	$ 11.2