Segment Information - Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Other charges & recoveries, net	$ (0.1)	$ 0.0	$ (0.1)	$ 0.0
Net revenue	477.4	379.4	742.8	568.7
Churchill Downs
Segment Reporting Information [Line Items]
Net revenue	193.1	164.3	214.5	166.6
Taxes & purses	35.7	27.3	41.9	28.0
Marketing & advertising	3.6	3.2	4.7	3.5
Salaries & benefits	12.5	9.7	17.7	12.8
Content expense	0.8	0.9	1.3	1.3
SG&A expense	2.0	1.2	3.7	2.2
Other operating expense	16.6	14.2	21.9	17.0
Other income	0.0	0.1	0.0	0.1
Adjusted EBITDA by segment	121.9	107.9	123.3	101.9
Online Wagering
Segment Reporting Information [Line Items]
Net revenue	96.0	94.1	159.4	157.7
Taxes & purses	4.3	4.6	7.6	8.0
Marketing & advertising	4.5	3.1	5.5	3.9
Salaries & benefits	2.7	2.4	5.2	4.5
Content expense	51.8	49.8	83.9	82.0
SG&A expense	1.9	1.6	3.7	3.0
Other operating expense	8.6	8.2	14.4	14.0
Other income	0.0	0.0	0.0	0.0
Adjusted EBITDA by segment	22.2	24.4	39.1	42.3
Gaming
Segment Reporting Information [Line Items]
Net revenue	177.8	108.2	347.9	220.7
Taxes & purses	68.5	35.5	133.5	73.5
Marketing & advertising	5.1	3.5	10.2	7.1
Salaries & benefits	25.4	15.6	49.9	32.5
Content expense	1.7	1.1	2.9	2.0
SG&A expense	6.9	4.0	13.3	7.8
Other operating expense	21.8	15.7	40.8	29.4
Other income	27.7	12.9	43.6	23.7
Adjusted EBITDA by segment	$ 76.1	$ 45.7	$ 140.9	$ 92.1