Segment Information - Reconciliation of Comprehensive Income to Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Net revenue	$ 364.1	$ 324.3
Adjusted EBITDA	128.5	110.6
Net income and comprehensive income	42.1	36.1
Depreciation and amortization	25.1	26.0
Interest expense	21.3	19.4
Income tax provision	16.5	16.2
EBITDA	105.0	97.7
Stock-based compensation expense	7.0	5.5
Pre-opening expense	2.1	0.6
Other expenses, net	2.5	0.0
Asset impairments	4.9	0.0
Transaction expense, net	5.0	0.1
Interest, depreciation and amortization expense related to equity investments	11.1	9.6
Changes in fair value of Rivers Des Plaines' interest rate swaps	(10.4)	(4.2)
Rivers Des Plaines' legal reserves and transaction costs	0.3	1.3
Other charges	1.0	0.0
Total adjustments to EBITDA	23.5	12.9
Adjusted EBITDA	128.5	110.6
Operating Segments
Segment Reporting Information [Line Items]
Net revenue	364.1	324.3
Adjusted EBITDA	143.1	123.8
Adjusted EBITDA	143.1	123.8
All Other
Segment Reporting Information [Line Items]
Net revenue	0.5	5.6
Adjusted EBITDA	(14.6)	(13.2)
Adjusted EBITDA	(14.6)	(13.2)
Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue	87.2	64.7
Taxes and purses	(26.8)	(20.0)
Marketing and advertising	(2.9)	(2.1)
Salaries and benefits	(10.9)	(10.0)
Content expense	(0.6)	(0.6)
Selling, general and administrative expense	(3.3)	(3.0)
Other operating expense	(14.8)	(10.7)
Other income	0.0	0.0
Adjusted EBITDA	27.9	18.3
Adjusted EBITDA	27.9	18.3
Live and Historical Racing | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	86.0	63.2
Adjusted EBITDA	27.9	18.3
Adjusted EBITDA	27.9	18.3
TwinSpires
Segment Reporting Information [Line Items]
Net revenue	101.4	105.0
Taxes and purses	(7.5)	(6.4)
Marketing and advertising	(5.1)	(8.5)
Salaries and benefits	(6.7)	(6.2)
Content expense	(43.1)	(46.5)
Selling, general and administrative expense	(2.6)	(2.6)
Other operating expense	(12.3)	(11.7)
Other income	0.0	0.0
Adjusted EBITDA	24.1	23.1
Asset impairments	4.9
Adjusted EBITDA	24.1	23.1
TwinSpires | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	100.3	103.5
Adjusted EBITDA	24.1	23.1
Adjusted EBITDA	24.1	23.1
Gaming
Segment Reporting Information [Line Items]
Net revenue	179.2	154.0
Taxes and purses	(67.3)	(59.3)
Marketing and advertising	(3.5)	(1.4)
Salaries and benefits	(23.9)	(19.9)
Content expense	(1.5)	(1.0)
Selling, general and administrative expense	(6.6)	(6.0)
Other operating expense	(20.0)	(15.5)
Other income	34.7	31.5
Adjusted EBITDA	91.1	82.4
Adjusted EBITDA	91.1	82.4
Gaming | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	177.3	152.0
Adjusted EBITDA	91.1	82.4
Adjusted EBITDA	$ 91.1	$ 82.4