Segment Information - Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Net revenue	$ 265.4	$ 189.3
Churchill Downs
Segment Reporting Information [Line Items]
Net revenue	21.4	2.3
Taxes & purses	6.2	0.7
Marketing & advertising	1.1	0.3
Salaries & benefits	5.2	3.1
Content expense	0.5	0.4
SG&A expense	1.7	1.0
Other operating expense	5.3	2.8
Other income	0.0	0.0
Adjusted EBITDA by segment	1.4	(6.0)
Online Wagering
Segment Reporting Information [Line Items]
Net revenue	63.4	63.6
Taxes & purses	3.3	3.4
Marketing & advertising	1.0	0.8
Salaries & benefits	2.5	2.1
Content expense	32.1	32.2
SG&A expense	1.8	1.4
Other operating expense	5.8	5.8
Other income	0.0	0.0
Adjusted EBITDA by segment	16.9	17.9
Gaming
Segment Reporting Information [Line Items]
Net revenue	170.1	112.5
Taxes & purses	65.0	38.0
Marketing & advertising	5.1	3.6
Salaries & benefits	24.5	16.9
Content expense	1.2	0.9
SG&A expense	6.4	3.8
Other operating expense	19.0	13.7
Other income	15.9	10.8
Adjusted EBITDA by segment	$ 64.8	$ 46.4