Segment Information - Reconciliation of Comprehensive Income to Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Net revenue	$ 383.1		$ 393.0		$ 1,329.7	$ 1,232.4
Adjusted EBITDA	163.2		156.1		582.9	500.0
Net income and comprehensive income	57.0		61.4		438.4	205.8
Depreciation and amortization	27.5		25.9		78.7	77.9
Interest expense	36.2		21.7		92.6	63.1
Income tax provision	16.4		26.3		173.5	84.1
EBITDA	137.1		135.3		783.2	430.9
Stock-based compensation expense	9.1		7.8		23.5	20.4
Pre-opening expense	4.2		1.7		8.9	3.8
Other expenses, net	1.4		0.0		5.7	0.2
Asset impairments	0.0		0.0		4.9	11.2
Transaction expense, net	1.2		2.0		7.4	2.1
Interest, depreciation and amortization expense related to equity investments	10.1		10.7		31.7	30.8
Changes in fair value of Rivers Des Plaines' interest rate swaps	0.0		(2.0)		(12.6)	(8.0)
Other charges	0.0		0.0		1.0	0.0
Gain on Calder land sale	0.0		0.0		(274.6)	0.0
Total adjustments to EBITDA	26.1		20.8		(200.3)	69.1
Operating Segments
Segment Reporting Information [Line Items]
Net revenue	383.1		393.0		1,329.7	1,232.4
Adjusted EBITDA	177.2		160.5		624.9	527.1
All Other
Segment Reporting Information [Line Items]
Net revenue	1.2		20.5		2.2	38.5
Adjusted EBITDA	(14.0)		(4.4)		(42.0)	(27.1)
Live and Historical Racing:
Segment Reporting Information [Line Items]
Net revenue	102.4		81.5		465.5	336.7
Taxes and purses	(31.6)		(24.6)		(118.0)	(95.4)
Marketing and advertising	(3.6)		(2.9)		(12.9)	(9.9)
Salaries and benefits	(13.3)		(10.9)		(43.1)	(36.2)
Content expense	(0.6)		(0.5)		(2.2)	(1.9)
Selling, general and administrative expense	(3.4)		(3.1)		(9.7)	(9.2)
Other operating expense	(15.6)		(11.8)		(53.6)	(39.8)
Other income	0.2		0.0		0.3	0.1
Adjusted EBITDA	34.5		27.7		226.3	144.4
Asset impairments				$ 11.2
Live and Historical Racing: | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	92.3		79.7		439.2	318.8
Adjusted EBITDA	34.5		27.7		226.3	144.4
TwinSpires
Segment Reporting Information [Line Items]
Net revenue	107.4		109.0		347.3	356.6
Taxes and purses	(6.6)		(8.0)		(21.3)	(22.7)
Marketing and advertising	(1.3)		(10.6)		(11.4)	(35.8)
Salaries and benefits	(6.3)		(7.0)		(19.9)	(20.0)
Content expense	(49.3)		(47.1)		(160.5)	(162.1)
Selling, general and administrative expense	(2.7)		(2.6)		(7.9)	(8.1)
Other operating expense	(10.1)		(11.6)		(37.2)	(38.1)
Other income	0.0		0.0		0.0	0.0
Adjusted EBITDA	31.1		22.1		89.1	69.8
Asset impairments		$ 4.9
TwinSpires | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	106.2		107.5		343.3	351.8
Adjusted EBITDA	31.1		22.1		89.1	69.8
Gaming
Segment Reporting Information [Line Items]
Net revenue	185.9		185.6		549.6	525.6
Taxes and purses	(70.6)		(71.8)		(206.1)	(201.1)
Marketing and advertising	(4.1)		(3.6)		(11.3)	(7.5)
Salaries and benefits	(24.6)		(22.5)		(72.0)	(63.0)
Content expense	(2.7)		(1.2)		(6.4)	(3.5)
Selling, general and administrative expense	(7.1)		(7.1)		(20.4)	(19.0)
Other operating expense	(21.7)		(19.7)		(63.9)	(52.9)
Other income	56.5		51.0		140.0	134.3
Adjusted EBITDA	111.6		110.7		309.5	312.9
Gaming | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	183.4		185.3		545.0	523.3
Adjusted EBITDA	111.6		110.7		309.5	312.9
Rivers Des Plaines
Segment Reporting Information [Line Items]
Legal reserve	0.1		0.6		0.6	8.6
All Other
Segment Reporting Information [Line Items]
Legal reserve	$ 0.0		$ 0.0		$ 3.2	$ 0.0