Segment Information - Net Revenue From External Customers and Intercompany Revenue From Each Operating Segment (Details) slot_machine in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($) segment	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) segment	Dec. 31, 2020 segment	Dec. 31, 2020 segment slot_machine	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2020	Dec. 31, 2020 sportsbook	Dec. 31, 2020 numberOfTableGames	Dec. 31, 2020 state	Mar. 06, 2019	Mar. 05, 2019
Segment Reporting Information [Line Items]
Number of reportable segments | segment										3
Number of slot machines										11,000	11
Number of table games	200								200	200	200					200
Number of states in which entity operates	8								8	8	8						8
Net revenues	$ 278.2	$ 337.8	$ 185.1	$ 252.9	$ 280.6	$ 306.3	$ 477.4	$ 265.4	$ 1,054.0			$ 1,329.7	$ 1,009.0
Intercompany net revenues									0.0			0.0	0.0
Other revenue									13.1			$ 33.4	26.1
Midwest Gaming Holdings, LLC
Segment Reporting Information [Line Items]
Equity method investment, ownership percentage					61.30%							61.30%		61.30%				61.30%	42.00%
Miami Valley Gaming LLC
Segment Reporting Information [Line Items]
Equity method investment, ownership percentage					50.00%							50.00%		50.00%
Gaming
Segment Reporting Information [Line Items]
Net revenues									441.4			$ 692.4	449.5
All Other
Segment Reporting Information [Line Items]
Net revenues									61.5			72.6	73.5
External Customer
Segment Reporting Information [Line Items]
Net revenues									1,054.0			1,329.7	1,009.0
External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenues									475.1			407.9	403.5
External Customer | Historical racing
Segment Reporting Information [Line Items]
Net revenues									93.6			81.6	13.8
External Customer | Racing event-related services
Segment Reporting Information [Line Items]
Net revenues									24.7			128.4	124.9
External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenues									392.6			585.8	365.9
External Customer | All Other
Segment Reporting Information [Line Items]
Net revenues									68.0			126.0	100.9
Churchill Downs
Segment Reporting Information [Line Items]
Net revenues									160.5			289.4	208.5
Online Wagering
Segment Reporting Information [Line Items]
Number of sportsbooks | sportsbook															3
Net revenues									409.9			291.6	291.5
Gaming
Segment Reporting Information [Line Items]
Net revenues									443.9			694.8	451.2
Gaming | MISSISSIPPI
Segment Reporting Information [Line Items]
Number of sportsbooks | sportsbook															2
Operating Segments
Segment Reporting Information [Line Items]
Net revenues									1,054.0			1,329.7	1,009.0
Operating Segments | External Customer
Segment Reporting Information [Line Items]
Net revenues									992.5			1,257.1	935.5
Operating Segments | External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenues									449.8			366.8	360.4
Operating Segments | External Customer | Historical racing
Segment Reporting Information [Line Items]
Net revenues									76.0			81.6	13.8
Operating Segments | External Customer | Racing event-related services
Segment Reporting Information [Line Items]
Net revenues									24.4			122.8	119.1
Operating Segments | External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenues									392.6			585.8	365.9
Operating Segments | External Customer | All Other
Segment Reporting Information [Line Items]
Net revenues									49.7			100.1	76.3
Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenues									142.8			274.2	195.8
Intercompany net revenues									17.7			15.2	12.7
Operating Segments | Churchill Downs | External Customer
Segment Reporting Information [Line Items]
Net revenues									142.8			274.2	195.8
Operating Segments | Churchill Downs | External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenues									39.4			59.0	54.9
Operating Segments | Churchill Downs | External Customer | Historical racing
Segment Reporting Information [Line Items]
Net revenues									76.0			81.6	13.8
Operating Segments | Churchill Downs | External Customer | Racing event-related services
Segment Reporting Information [Line Items]
Net revenues									21.0			118.7	115.2
Operating Segments | Churchill Downs | External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenues									0.0			0.0	0.0
Operating Segments | Churchill Downs | External Customer | All Other
Segment Reporting Information [Line Items]
Net revenues									6.4			14.9	11.9
Operating Segments | Churchill Downs | Churchill Downs Racetrack
Segment Reporting Information [Line Items]
Net revenues									63.3			187.6	181.0
Operating Segments | Churchill Downs | Derby City Gaming
Segment Reporting Information [Line Items]
Net revenues									79.5			86.6	14.8
Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenues									408.3			290.5	290.2
Intercompany net revenues									1.6			1.1	1.3
Operating Segments | Online Wagering | External Customer
Segment Reporting Information [Line Items]
Net revenues									408.3			290.5	290.2
Operating Segments | Online Wagering | External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenues									387.5			277.1	278.4
Operating Segments | Online Wagering | External Customer | Historical racing
Segment Reporting Information [Line Items]
Net revenues									0.0			0.0	0.0
Operating Segments | Online Wagering | External Customer | Racing event-related services
Segment Reporting Information [Line Items]
Net revenues									0.0			0.0	0.0
Operating Segments | Online Wagering | External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenues									5.1			0.6	0.0
Operating Segments | Online Wagering | External Customer | All Other
Segment Reporting Information [Line Items]
Net revenues									15.7			12.8	11.8
Operating Segments | Online Wagering | TwinSpires Horse Racing
Segment Reporting Information [Line Items]
Net revenues									403.4			289.9	290.2
Operating Segments | Online Wagering | TwinSpires Sports and Casino
Segment Reporting Information [Line Items]
Net revenues									4.9			0.6	0.0
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenues									441.4			692.4	449.5
Intercompany net revenues									2.5			2.4	1.7
Operating Segments | Gaming | External Customer
Segment Reporting Information [Line Items]
Net revenues									441.4			692.4	449.5
Operating Segments | Gaming | External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenues									22.9			30.7	27.1
Operating Segments | Gaming | External Customer | Historical racing
Segment Reporting Information [Line Items]
Net revenues									0.0			0.0	0.0
Operating Segments | Gaming | External Customer | Racing event-related services
Segment Reporting Information [Line Items]
Net revenues									3.4			4.1	3.9
Operating Segments | Gaming | External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenues									387.5			585.2	365.9
Operating Segments | Gaming | External Customer | All Other
Segment Reporting Information [Line Items]
Net revenues									27.6			72.4	52.6
Operating Segments | Gaming | Oxford Casino
Segment Reporting Information [Line Items]
Net revenues									44.9			101.7	102.0
Operating Segments | Gaming | Riverwalk Casino
Segment Reporting Information [Line Items]
Net revenues									49.1			58.9	54.5
Operating Segments | Gaming | Harlow’s Casino
Segment Reporting Information [Line Items]
Net revenues									41.8			55.3	50.2
Operating Segments | Gaming | Calder
Segment Reporting Information [Line Items]
Net revenues									51.8			99.8	98.6
Intercompany net revenues									0.1			0.1	0.1
Operating Segments | Gaming | Fair Grounds and VSI
Segment Reporting Information [Line Items]
Net revenues									97.6			123.0	117.7
Intercompany net revenues									2.2			1.8	1.6
Operating Segments | Gaming | Saratoga
Segment Reporting Information [Line Items]
Net revenues									0.0			0.0	0.6
Operating Segments | Gaming | Lady Luck Nemacolin
Segment Reporting Information [Line Items]
Net revenues									20.7			29.3	0.0
Operating Segments | Gaming | Presque Isle
Segment Reporting Information [Line Items]
Net revenues									75.2			138.5	0.0
Intercompany net revenues									0.2			0.5	0.0
Operating Segments | Gaming | Ocean Downs
Segment Reporting Information [Line Items]
Net revenues									60.3			85.9	25.9
All Other
Segment Reporting Information [Line Items]
Net revenues									61.5			72.6	73.5
Intercompany net revenues									13.2			11.6	11.2
All Other | External Customer
Segment Reporting Information [Line Items]
Net revenues									61.5			72.6	73.5
All Other | External Customer | Pari-mutuel, live and simulcast racing
Segment Reporting Information [Line Items]
Net revenues									25.3			41.1	43.1
All Other | External Customer | Historical racing
Segment Reporting Information [Line Items]
Net revenues									17.6			0.0	0.0
All Other | External Customer | Racing event-related services
Segment Reporting Information [Line Items]
Net revenues									0.3			5.6	5.8
All Other | External Customer | Gaming
Segment Reporting Information [Line Items]
Net revenues									0.0			0.0	0.0
All Other | External Customer | All Other
Segment Reporting Information [Line Items]
Net revenues									18.3			25.9	24.6
Intersegment Eliminations
Segment Reporting Information [Line Items]
Intercompany net revenues									$ (35.0)			$ (30.3)	$ (26.9)