Segment Information - Reconciliation of Comprehensive Income to Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Net income and comprehensive income	$ 143.0	$ 339.3	$ 298.7	$ 381.4
Depreciation and amortization	41.8	26.1	79.7	51.2
Interest expense, net	65.2	35.1	129.9	56.4
Income tax provision	56.2	140.6	109.4	157.1
EBITDA	306.2	541.1	617.7	646.1
Stock-based compensation expense	8.1	7.4	16.7	14.4
Pre-opening expense	3.2	2.6	6.4	4.7
Arlington exit costs	5.9	1.8	9.3	4.3
Other expenses, net	6.6	0.0	6.9	0.0
Transaction expense, net	0.5	1.2	0.3	6.2
Asset impairments	24.5	0.0	24.5	4.9
Interest, depreciation and amortization expense related to equity investments	9.9	10.5	19.7	21.6
Changes in fair value of Rivers Des Plaines' interest rate swaps	0.0	(2.2)	0.0	(12.6)
Other charges and recoveries, net	(1.2)	0.0	(0.9)	1.0
Gain on sale of assets	0.0	(274.6)	(114.0)	(274.6)
Total adjustments to EBITDA	57.5	(249.9)	(31.1)	(226.4)
Adjusted EBITDA	363.7	291.2	586.6	419.7
Net revenue	768.5	582.5	1,328.0	946.6
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	380.8	304.6	621.8	447.7
All Other
Segment Reporting Information [Line Items]
Adjusted EBITDA	(17.1)	(13.4)	(35.2)	(28.0)
Net revenue	0.2	0.5	0.5	1.0
Live and Historical
Segment Reporting Information [Line Items]
Adjusted EBITDA	223.5	163.9	305.6	191.8
Net revenue	408.0	275.9	623.8	363.1
Taxes and purses	(85.4)	(59.6)	(141.9)	(86.4)
Marketing and advertising	(12.1)	(6.4)	(20.3)	(9.3)
Salaries and benefits	(30.3)	(18.9)	(52.1)	(29.8)
Content expense	(2.0)	(1.0)	(3.5)	(1.6)
Selling, general and administrative expense	(7.3)	(3.0)	(16.0)	(6.3)
Other operating expense	(47.6)	(23.2)	(84.6)	(38.0)
Other income	0.2	0.1	0.2	0.1
Live and Historical | Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	223.5	163.9	305.6	191.8
Net revenue	385.0	260.9	599.4	346.9
TwinSpires
Segment Reporting Information [Line Items]
Adjusted EBITDA	33.9	33.9	63.3	58.0
Net revenue	139.1	138.5	235.5	239.9
Taxes and purses	(7.0)	(7.2)	(12.0)	(14.7)
Marketing and advertising	(5.3)	(5.0)	(6.7)	(10.1)
Salaries and benefits	(7.5)	(6.9)	(13.7)	(13.6)
Content expense	(68.7)	(68.1)	(111.7)	(111.2)
Selling, general and administrative expense	(2.7)	(2.6)	(5.1)	(5.2)
Other operating expense	(14.0)	(14.8)	(24.0)	(27.1)
Other income	0.0	0.0	1.0	0.0
TwinSpires | Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	33.9	33.9	63.3	58.0
Net revenue	137.4	136.8	232.2	237.1
Gaming
Segment Reporting Information [Line Items]
Adjusted EBITDA	123.4	106.8	252.9	197.9
Net revenue	247.9	184.5	499.5	363.7
Taxes and purses	(81.7)	(68.2)	(165.3)	(135.5)
Marketing and advertising	(9.0)	(3.7)	(17.6)	(7.2)
Salaries and benefits	(39.5)	(23.5)	(74.0)	(47.4)
Content expense	(2.7)	(2.2)	(4.5)	(3.7)
Selling, general and administrative expense	(10.3)	(6.7)	(22.5)	(13.3)
Other operating expense	(30.0)	(22.2)	(60.0)	(42.2)
Other income	48.7	48.8	97.3	83.5
Gaming | Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	123.4	106.8	252.9	197.9
Net revenue	245.9	184.3	495.9	361.6
Rivers Des Plaines
Segment Reporting Information [Line Items]
Rivers Des Plaines' legal reserves and transaction costs	0.0	0.2	0.0	0.5
Other Segments [Member]
Segment Reporting Information [Line Items]
Legal reserve	$ 0.0	$ 3.2	$ 0.0	$ 3.2