Segment Information - Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 252.9	$ 265.4
Churchill Downs
Segment Reporting Information [Line Items]
Revenues	23.8	21.4
Taxes and purses	(7.1)	(6.2)
Marketing and advertising	(1.1)	(1.1)
Salaries and benefits	(6.2)	(5.2)
Content Expense	(0.4)	(0.5)
Adjusted EBITDA Selling, General & Administrative Expenses	(1.5)	(1.7)
Other Cost and Expense, Operating	(5.6)	(5.3)
Other income	0.0	0.0
Adjusted EBITDA	1.9	1.4
Online Wagering
Segment Reporting Information [Line Items]
Revenues	67.7	63.4
Taxes and purses	(3.9)	(3.3)
Marketing and advertising	(3.5)	(1.0)
Salaries and benefits	(3.5)	(2.5)
Content Expense	(33.2)	(32.1)
Adjusted EBITDA Selling, General & Administrative Expenses	(1.4)	(1.8)
Other Cost and Expense, Operating	(7.2)	(5.8)
Other income	0.0	0.0
Adjusted EBITDA	15.0	16.9
Gaming
Segment Reporting Information [Line Items]
Revenues	149.1	170.1
Taxes and purses	(59.1)	(65.0)
Marketing and advertising	(5.3)	(5.1)
Salaries and benefits	(29.5)	(24.5)
Content Expense	(1.2)	(1.2)
Adjusted EBITDA Selling, General & Administrative Expenses	(6.7)	(6.4)
Other Cost and Expense, Operating	(19.5)	(19.0)
Other income	21.2	15.9
Adjusted EBITDA	$ 49.0	$ 64.8