Segment Information - Schedule of Net Revenue from External Customers (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 337.8	$ 306.3	$ 775.8	$ 1,049.1
Disclosure of complimentary revenue	2.1	8.9	10.5	24.7
Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	68.0	32.7	122.0	247.2
Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	126.4	70.4	315.7	229.8
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	134.9	178.6	321.3	526.5
Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	337.8	306.3	775.8	1,049.1
Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	60.8	31.4	107.6	234.6
Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	125.9	70.2	314.4	228.9
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	134.8	178.3	319.7	524.7
Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	16.3	26.4	34.1	60.9
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	134.8	178.3	319.7	524.7
Other
Segment Reporting Information [Line Items]
Net revenue from external customers	16.3	26.4	34.1	60.9
External Customer
Segment Reporting Information [Line Items]
Net revenue from external customers	337.8	306.3	775.8	1,049.1
External Customer | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	60.8	31.4	107.6	234.6
External Customer | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	125.9	70.2	314.4	228.9
External Customer | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	134.8	178.3	319.7	524.7
External Customer | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	321.5	279.9	741.7	988.2
External Customer | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	16.3	26.4	34.1	60.9
External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenue from external customers	146.9	93.7	364.6	325.4
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	14.3	5.4	30.2	48.1
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	119.0	67.1	298.5	218.7
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	4.6	6.2	16.2	23.9
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	137.9	78.7	344.9	290.7
External Customer | Pari-mutuel, live and simulcast racing | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	9.0	15.0	19.7	34.7
External Customer | Pari-mutuel, historical racing
Segment Reporting Information [Line Items]
Net revenue from external customers	27.1	21.3	54.8	58.7
External Customer | Pari-mutuel, historical racing | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	24.9	21.3	52.6	58.7
External Customer | Pari-mutuel, historical racing | Operating Segments | Online Wagering
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 | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	24.9	21.3	52.6	58.7
External Customer | Pari-mutuel, historical racing | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	2.2	0.0	2.2	0.0
External Customer | Racing event-related services
Segment Reporting Information [Line Items]
Net revenue from external customers	20.0	5.5	22.6	123.4
External Customer | Racing event-related services | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	19.1	1.6	19.6	115.0
External Customer | Racing event-related services | Operating Segments | Online Wagering
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	0.7	0.8	2.7	3.1
External Customer | Racing event-related services | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	19.8	2.4	22.3	118.1
External Customer | Racing event-related services | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	0.2	3.1	0.3	5.3
External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	125.2	153.2	282.3	442.5
External Customer | Gaming | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0	0.0	0.0
External Customer | Gaming | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	1.6	0.0	3.8	0.1
External Customer | Gaming | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	123.6	153.2	278.5	442.4
External Customer | Gaming | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	125.2	153.2	282.3	442.5
External Customer | Gaming | Segment Reconciling Items | 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	18.6	32.6	51.5	99.1
External Customer | Other | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	2.5	3.1	5.2	12.8
External Customer | Other | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	5.3	3.1	12.1	10.1
External Customer | Other | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	5.9	18.1	22.3	55.3
External Customer | Other | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	13.7	24.3	39.6	78.2
External Customer | Other | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 4.9	$ 8.3	$ 11.9	$ 20.9