Segment Information - Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net revenue	$ 337.8	$ 306.3	$ 775.8	$ 1,049.1
Churchill Downs
Segment Reporting Information [Line Items]
Net revenue	68.0	32.7	122.0	247.2
Taxes and purses	(19.3)	(10.2)	(40.3)	(52.1)
Marketing and advertising	(2.3)	(1.1)	(3.7)	(5.8)
Salaries and benefits	(8.4)	(6.8)	(19.5)	(24.5)
Content expense	(0.2)	(0.5)	(0.7)	(1.8)
Selling, general and administrative expense	(2.6)	(2.1)	(5.3)	(5.8)
Other operating expense	(11.3)	(6.9)	(22.2)	(28.8)
Other income	0.0	0.1	0.0	0.1
Adjusted EBITDA	23.9	5.2	30.3	128.5
Online Wagering
Segment Reporting Information [Line Items]
Net revenue	126.4	70.4	315.7	229.8
Taxes and purses	(8.0)	(4.4)	(18.5)	(12.0)
Marketing and advertising	(6.9)	(3.6)	(13.3)	(9.1)
Salaries and benefits	(3.1)	(3.0)	(9.6)	(8.2)
Content expense	(63.5)	(36.5)	(156.4)	(120.4)
Selling, general and administrative expense	(3.6)	(1.8)	(6.7)	(5.5)
Other operating expense	(9.4)	(6.1)	(25.6)	(20.5)
Other income	0.0	0.0	0.1	0.0
Adjusted EBITDA	31.9	15.0	85.7	54.1
Gaming
Segment Reporting Information [Line Items]
Net revenue	134.9	178.6	321.3	526.5
Taxes and purses	(51.7)	(71.2)	(125.2)	(204.7)
Marketing and advertising	(0.6)	(5.5)	(6.3)	(15.7)
Salaries and benefits	(19.1)	(26.6)	(57.6)	(76.5)
Content expense	(1.3)	(1.6)	(2.9)	(4.5)
Selling, general and administrative expense	(8.3)	(7.9)	(18.9)	(21.2)
Other operating expense	(14.4)	(21.2)	(45.0)	(62.0)
Other income	35.9	27.1	57.0	70.7
Adjusted EBITDA	$ 75.4	$ 71.7	$ 122.4	$ 212.6