Segment Information - Reconciliation of Comprehensive Income to Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Net revenue	$ 582.5		$ 515.1	$ 946.6	$ 839.4
Adjusted EBITDA	291.2		233.3	419.7	343.9
Net income and comprehensive income	339.3		108.3	381.4	144.4
Depreciation and amortization	26.1		26.0	51.2	52.0
Interest expense	35.1		22.0	56.4	41.4
Income tax provision	140.6		41.6	157.1	57.8
EBITDA	541.1		197.9	646.1	295.6
Stock-based compensation expense	7.4		7.1	14.4	12.6
Pre-opening expense	2.6		1.5	4.7	2.1
Other expenses, net	1.8		0.2	4.3	0.2
Asset impairments	0.0		11.2	4.9	11.2
Transaction expense, net	1.2		0.0	6.2	0.1
Interest, depreciation and amortization expense related to equity investments	10.5		10.5	21.6	20.1
Changes in fair value of Rivers Des Plaines' interest rate swaps	(2.2)		(1.8)	(12.6)	(6.0)
Other charges	0.0		0.0	1.0	0.0
Gain on Calder land sale	(274.6)		0.0	(274.6)	0.0
Total adjustments to EBITDA	(249.9)		35.4	(226.4)	48.3
Operating Segments
Segment Reporting Information [Line Items]
Net revenue	582.5		515.1	946.6	839.4
Adjusted EBITDA	304.6		242.8	447.7	366.6
All Other
Segment Reporting Information [Line Items]
Net revenue	0.5		12.4	1.0	18.0
Adjusted EBITDA	(13.4)		(9.5)	(28.0)	(22.7)
Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue	275.9		190.5	363.1	255.2
Taxes and purses	(59.6)		(50.8)	(86.4)	(70.8)
Marketing and advertising	(6.4)		(4.9)	(9.3)	(7.0)
Salaries and benefits	(18.9)		(15.3)	(29.8)	(25.3)
Content expense	(1.0)		(0.8)	(1.6)	(1.4)
Selling, general and administrative expense	(3.0)		(3.1)	(6.3)	(6.1)
Other operating expense	(23.2)		(17.3)	(38.0)	(28.0)
Other income	0.1		0.1	0.1	0.1
Adjusted EBITDA	163.9		98.4	191.8	116.7
Asset impairments	11.2
Live and Historical Racing | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	260.9		175.9	346.9	239.1
Adjusted EBITDA	163.9		98.4	191.8	116.7
TwinSpires
Segment Reporting Information [Line Items]
Net revenue	138.5		142.6	239.9	247.6
Taxes and purses	(7.2)		(8.3)	(14.7)	(14.7)
Marketing and advertising	(5.0)		(16.7)	(10.1)	(25.2)
Salaries and benefits	(6.9)		(6.8)	(13.6)	(13.0)
Content expense	(68.1)		(68.5)	(111.2)	(115.0)
Selling, general and administrative expense	(2.6)		(2.9)	(5.2)	(5.5)
Other operating expense	(14.8)		(14.8)	(27.1)	(26.5)
Other income	0.0		0.0	0.0	0.0
Adjusted EBITDA	33.9		24.6	58.0	47.7
Asset impairments		$ 4.9
TwinSpires | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	136.8		140.8	237.1	244.3
Adjusted EBITDA	33.9		24.6	58.0	47.7
Gaming
Segment Reporting Information [Line Items]
Net revenue	184.5		186.0	363.7	340.0
Taxes and purses	(68.2)		(70.0)	(135.5)	(129.3)
Marketing and advertising	(3.7)		(2.5)	(7.2)	(3.9)
Salaries and benefits	(23.5)		(20.6)	(47.4)	(40.5)
Content expense	(2.2)		(1.3)	(3.7)	(2.3)
Selling, general and administrative expense	(6.7)		(5.9)	(13.3)	(11.9)
Other operating expense	(22.2)		(17.7)	(42.2)	(33.2)
Other income	48.8		51.8	83.5	83.3
Adjusted EBITDA	106.8		119.8	197.9	202.2
Gaming | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	184.3		186.0	361.6	338.0
Adjusted EBITDA	106.8		119.8	197.9	202.2
Rivers Des Plaines
Segment Reporting Information [Line Items]
Legal reserve	0.2		6.7	0.5	8.0
All Other
Segment Reporting Information [Line Items]
Legal reserve	$ 3.2		$ 0.0	$ 3.2	$ 0.0