Segment Information - Reconciliation of Comprehensive Income to Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net income and comprehensive income				$ 417.3	$ 439.4	$ 249.1
Depreciation and amortization				169.0	113.7	103.2
Interest expense, net				268.4	147.3	84.7
Income tax provision				144.5	169.4	94.5
EBITDA				999.2	869.8	531.5
Stock-based compensation expense				32.9	31.8	27.8
Legal reserve				(1.2)	3.8	0.0
Pre-opening expense				18.6	13.2	5.8
Arlington exit costs				9.4	5.7	5.3
Other expenses, net				7.0	1.7	0.2
Transaction expense, net				4.8	42.1	2.6
Non-cash impairment charge				24.6	38.3	15.3
Interest, depreciation and amortization expense related to equity investments				40.2	42.8	41.5
Other charges and recoveries, net				2.4	1.0	0.0
Gain on sale of assets				(114.0)	(274.6)	0.0
Total adjustments to EBITDA				24.7	(106.2)	95.5
Adjusted EBITDA				1,023.9	763.6	627.0
Rivers Des Plaines
Segment Reporting Information [Line Items]
Changes in fair value of Rivers Des Plaines' interest rate swaps				0.0	(12.6)	(12.9)
Rivers Des Plaines' legal reserves and transaction costs				0.0	0.6	9.9
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA				1,096.1	823.5	669.6
All Other
Segment Reporting Information [Line Items]
Adjusted EBITDA				(72.2)	(59.9)	(42.6)
Live and Historical Racing
Segment Reporting Information [Line Items]
Non-cash impairment charge			$ 11.2
Live and Historical Racing | Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA				475.4	287.5	175.0
TwinSpires
Segment Reporting Information [Line Items]
Non-cash impairment charge	$ 4.9	$ 4.1
TwinSpires | Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA				132.1	114.1	82.7
Gaming | Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA				$ 488.6	$ 421.9	$ 411.9