Segment Information - Schedule of Net Revenue from External Customers (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 477.4	$ 379.4	$ 742.8	$ 568.7
Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	193.1	164.3	214.5	166.6
Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	96.0	94.1	159.4	157.7
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	177.8	108.2	347.9	220.7
Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	477.4	379.4	742.8	568.7
Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	182.2	154.9	203.2	156.9
Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	95.6	93.7	158.7	156.9
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	177.6	108.1	346.4	219.6
Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	22.0	22.7	34.5	35.3
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	177.6	108.1	346.4	219.6
Other
Segment Reporting Information [Line Items]
Net revenue from external customers	22.0	22.7	34.5	35.3
External Customer
Segment Reporting Information [Line Items]
Net revenue from external customers	477.4	379.4	742.8	568.7
External Customer | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	182.2	154.9	203.2	156.9
External Customer | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	95.6	93.7	158.7	156.9
External Customer | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	177.6	108.1	346.4	219.6
External Customer | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	455.4	356.7	708.3	533.4
External Customer | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	22.0	22.7	34.5	35.3
External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenue from external customers	150.1	147.2	231.7	228.0
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	41.3	39.5	42.7	40.8
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	91.1	89.7	151.6	150.7
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	5.5	4.4	17.7	15.0
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	137.9	133.6	212.0	206.5
External Customer | Pari-mutuel, live and simulcast racing | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	12.2	13.6	19.7	21.5
External Customer | Pari-mutuel, historical racing
Segment Reporting Information [Line Items]
Net revenue from external customers	19.9	0.0	37.4	0.0
External Customer | Pari-mutuel, historical racing | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	19.9	0.0	37.4	0.0
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	19.9	0.0	37.4	0.0
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	116.4	112.5	117.9	113.9
External Customer | Racing event-related services | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	113.4	109.6	113.4	109.6
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	0.7	2.3	2.1
External Customer | Racing event-related services | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	114.2	110.3	115.7	111.7
External Customer | Racing event-related services | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	2.2	2.2	2.2	2.2
External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	150.2	87.1	289.3	175.0
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	150.2	87.1	289.2	175.0
External Customer | Gaming | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	150.2	87.1	289.3	175.0
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	40.8	32.6	66.5	51.8
External Customer | Other | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	7.6	5.8	9.7	6.5
External Customer | Other | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	4.5	4.0	7.0	6.2
External Customer | Other | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	21.1	15.9	37.2	27.5
External Customer | Other | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	33.2	25.7	53.9	40.2
External Customer | Other | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 7.6	$ 6.9	$ 12.6	$ 11.6