Segment Information - Schedule of Net Revenue from External Customers (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 252.9	$ 265.4
Disclosure of complimentary revenue	7.6	7.8
Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	23.8	21.4
Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	67.7	63.4
Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	149.1	170.1
Operating Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	252.9	265.4
Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	23.5	21.0
Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	67.3	63.1
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	147.6	168.8
Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	14.5	12.5
External Customer
Segment Reporting Information [Line Items]
Net revenue from external customers	252.9	265.4
External Customer | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	23.5	21.0
External Customer | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	67.3	63.1
External Customer | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	147.6	168.8
External Customer | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	238.4	252.9
External Customer | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	14.5	12.5
External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenue from external customers	84.7	81.6
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	1.0	1.4
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	63.9	60.5
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	9.9	12.2
External Customer | Pari-mutuel, live and simulcast racing | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	74.8	74.1
External Customer | Pari-mutuel, live and simulcast racing | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	9.9	7.5
External Customer | Pari-mutuel, historical racing
Segment Reporting Information [Line Items]
Net revenue from external customers	20.4	17.7
External Customer | Pari-mutuel, historical racing | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	20.4	17.7
External Customer | Pari-mutuel, historical racing | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
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 | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	20.4	17.7
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
External Customer | Racing event-related services
Segment Reporting Information [Line Items]
Net revenue from external customers	1.4	1.5
External Customer | Racing event-related services | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
External Customer | Racing event-related services | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
External Customer | Racing event-related services | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	1.3	1.5
External Customer | Racing event-related services | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	1.3	1.5
External Customer | Racing event-related services | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	0.1	0.0
External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	122.3	146.7
External Customer | Gaming | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0
External Customer | Gaming | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	0.7	0.1
External Customer | Gaming | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	121.6	146.6
External Customer | Gaming | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	122.3	146.7
External Customer | Gaming | Segment Reconciling Items | All Other
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	24.1	17.9
External Customer | Other | Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue from external customers	2.1	1.9
External Customer | Other | Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue from external customers	2.7	2.5
External Customer | Other | Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue from external customers	14.8	8.5
External Customer | Other | Operating Segments | Total Segments
Segment Reporting Information [Line Items]
Net revenue from external customers	19.6	12.9
External Customer | Other | Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 4.5	$ 5.0