Segment Information - Schedule of Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
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
Adjusted EBITDA									286.5	451.4	328.8
Churchill Downs
Segment Reporting Information [Line Items]
Net revenues									160.5	289.4	208.5
Online Wagering
Segment Reporting Information [Line Items]
Net revenues									409.9	291.6	291.5
Gaming
Segment Reporting Information [Line Items]
Net revenues									443.9	694.8	451.2
Operating Segments
Segment Reporting Information [Line Items]
Net revenues									1,054.0	1,329.7	1,009.0
Adjusted EBITDA									324.3	484.9	355.4
Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenues									142.8	274.2	195.8
Taxes and purses									(54.1)	(66.5)	(41.3)
Marketing and advertising									(4.1)	(7.1)	(5.7)
Salaries and benefits									(26.5)	(32.0)	(23.7)
Content expense									(1.0)	(2.4)	(2.2)
Selling, general and administrative expense									(7.0)	(8.0)	(5.3)
Other operating expense									(29.6)	(35.9)	(28.0)
Other income									0.1	0.2	0.1
Adjusted EBITDA									38.3	137.7	102.4
Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenues									408.3	290.5	290.2
Taxes and purses									(23.7)	(15.3)	(15.2)
Marketing and advertising									(16.5)	(12.2)	(6.0)
Salaries and benefits									(13.0)	(11.4)	(9.2)
Content expense									(204.9)	(152.8)	(152.0)
Selling, general and administrative expense									(8.9)	(7.2)	(5.9)
Other operating expense									(33.7)	(26.4)	(24.2)
Other income									0.1	0.0	0.0
Adjusted EBITDA									109.3	66.3	79.0
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenues									441.4	692.4	449.5
Taxes and purses									(173.0)	(270.3)	(153.4)
Marketing and advertising									(7.5)	(21.5)	(15.5)
Salaries and benefits									(75.9)	(103.3)	(68.9)
Content expense									(3.5)	(6.0)	(4.1)
Selling, general and administrative expense									(25.4)	(29.0)	(18.6)
Other operating expense									(60.8)	(84.1)	(60.0)
Other income									78.9	100.3	43.3
Adjusted EBITDA									$ 176.7	$ 280.9	$ 174.0