Segment Information - Schedule of Net Revenue from External Customers (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 306.3	$ 221.3	$ 1,049.1	$ 790.0
Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	32.7	11.8	247.2	178.4
Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	70.4	72.1	229.8	229.8
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	178.6	110.5	526.5	331.2
Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	306.3	221.3	1,049.1	790.0
Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	31.4	10.8	234.6	167.7
Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	70.2	71.8	228.9	228.7
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	178.3	110.4	524.7	330.0
Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	26.4	28.3	60.9	63.6
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	178.3	110.4	524.7	330.0
Other
Segment Reporting Information [Line Items]
Net revenue from external customers	26.4	28.3	60.9	63.6
External Customer
Segment Reporting Information [Line Items]
Net revenue from external customers	306.3	221.3	1,049.1	790.0
External Customer | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	31.4	10.8	234.6	167.7
External Customer | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	70.2	71.8	228.9	228.7
External Customer | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	178.3	110.4	524.7	330.0
External Customer | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	279.9	193.0	988.2	726.4
External Customer | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	26.4	28.3	60.9	63.6
External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenue from external customers	93.7	94.5	325.4	322.5
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	5.4	4.8	48.1	45.6
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	67.1	68.8	218.7	219.5
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	6.2	4.3	23.9	19.3
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	78.7	77.9	290.7	284.4
External Customer | Pari-mutuel, live and simulcast racing | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	15.0	16.6	34.7	38.1
External Customer | Pari-mutuel, historical racing
Segment Reporting Information [Line Items]
Net revenue from external customers	21.3	2.2	58.7	2.2
External Customer | Pari-mutuel, historical racing | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	21.3	2.2	58.7	2.2
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	21.3	2.2	58.7	2.2
External Customer | Pari-mutuel, historical racing | 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 | Racing event-related services
Segment Reporting Information [Line Items]
Net revenue from external customers	5.5	6.3	123.4	120.2
External Customer | Racing event-related services | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	1.6	2.0	115.0	111.6
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	0.8	0.8	3.1	2.9
External Customer | Racing event-related services | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	2.4	2.8	118.1	114.5
External Customer | Racing event-related services | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	3.1	3.5	5.3	5.7
External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	153.2	92.8	442.5	267.8
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	0.0	0.0	0.1	0.0
External Customer | Gaming | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	153.2	92.8	442.4	267.8
External Customer | Gaming | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	153.2	92.8	442.5	267.8
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	32.6	25.5	99.1	77.3
External Customer | Other | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	3.1	1.8	12.8	8.3
External Customer | Other | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	3.1	3.0	10.1	9.2
External Customer | Other | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	18.1	12.5	55.3	40.0
External Customer | Other | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	24.3	17.3	78.2	57.5
External Customer | Other | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 8.3	$ 8.2	$ 20.9	$ 19.8