Segment Information - Schedule of Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net revenues	$ 280.6	$ 306.3	$ 477.4	$ 265.4	$ 219.0	$ 221.3	$ 379.4	$ 189.3	$ 1,329.7	$ 1,009.0	$ 882.6
Adjusted EBITDA									451.4	328.8	286.2
Churchill Downs
Segment Reporting Information [Line Items]
Net revenues									289.4	208.5	172.7
Adjusted EBITDA									137.7	102.4	89.0
Online Wagering
Segment Reporting Information [Line Items]
Net revenues									291.6	291.5	256.7
Adjusted EBITDA									66.3	79.0	69.9
Gaming
Segment Reporting Information [Line Items]
Net revenues									694.8	451.2	390.9
Adjusted EBITDA									280.9	174.0	148.6
All Other
Segment Reporting Information [Line Items]
Adjusted EBITDA									484.9	355.4	307.5
Total Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA									(33.5)	(26.6)	(21.3)
Operating Segments
Segment Reporting Information [Line Items]
Net revenues									1,329.7	1,009.0	882.6
Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenues									274.2	195.8	161.3
Taxes and purses									(66.5)	(41.3)	(34.1)
Marketing and advertising									(7.1)	(5.7)	(2.7)
Salaries and benefits									(32.0)	(23.7)	(19.3)
Content expense									(2.4)	(2.2)	(2.4)
Selling, general and administrative expense									(8.0)	(5.3)	(4.0)
Other operating expense									(35.9)	(28.0)	(21.3)
Other income									0.2	0.1	0.1
Adjusted EBITDA									137.7	102.4	89.0
Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenues									290.5	290.2	255.6
Taxes and purses									(15.3)	(15.2)	(14.7)
Marketing and advertising									(12.2)	(6.0)	(8.2)
Salaries and benefits									(11.4)	(9.2)	(9.9)
Content expense									(152.8)	(152.0)	(125.0)
Selling, general and administrative expense									(7.2)	(5.9)	(6.9)
Other operating expense									(26.4)	(24.2)	(22.1)
Other income									0.0	0.0	0.0
Adjusted EBITDA									66.3	79.0	69.9
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenues									692.4	449.5	389.3
Taxes and purses									(270.3)	(153.4)	(130.7)
Marketing and advertising									(21.5)	(15.5)	(13.0)
Salaries and benefits									(103.3)	(68.9)	(63.4)
Content expense									(6.0)	(4.1)	(4.0)
Selling, general and administrative expense									(29.0)	(18.6)	(17.1)
Other operating expense									(84.1)	(60.0)	(56.1)
Other income									100.3	43.3	42.0
Adjusted EBITDA									$ 280.9	$ 174.0	$ 148.6