Segment Information - Reconciliation of Comprehensive Income to Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Net revenue	$ 393.0			$ 337.8			$ 1,232.4	$ 775.8
Adjusted EBITDA	156.1			121.9			500.0	207.3
Net income (loss) and comprehensive income (loss) attributable to Churchill Downs Incorporated	61.4			43.2			205.8	(99.0)
Net loss attributable to noncontrolling interest	0.0			0.1			0.0	0.2
Net income (loss) before noncontrolling interest	61.4	$ 108.3	$ 36.1	43.1	$ (118.8)	$ (23.5)	205.8	(99.2)
Loss from discontinued operations, net of tax	0.0			0.0			0.0	96.1
Net income (loss) from continuing operations	61.4			43.1			205.8	(3.1)
Depreciation and amortization	25.9			22.4			77.9	66.5
Interest expense	21.7			19.7			63.1	59.3
Income tax provision (benefit)	26.3			13.9			84.1	(5.6)
EBITDA	135.3			99.1			430.9	117.1
Stock-based compensation expense	7.8			6.9			20.4	17.3
Other charges	0.0			0.8			0.2	0.7
Pre-opening expense and other expense	1.7			6.2			3.8	9.8
Asset impairments	0.0			0.0			11.2	17.5
Transaction expense, net	2.0			0.5			2.1	1.0
Interest, depreciation and amortization expense related to equity investments	10.7			9.9			30.8	29.2
Changes in fair value of Rivers Des Plaines' interest rate swaps	(2.0)			(1.5)			(8.0)	14.7
Rivers Des Plaines' legal reserves and transaction costs	0.6			0.0			8.6	0.0
Total adjustments to EBITDA	20.8			22.8			69.1	90.2
Adjusted EBITDA	156.1			121.9			500.0	207.3
Operating Segments
Segment Reporting Information [Line Items]
Net revenue	393.0			337.8			1,232.4	775.8
Adjusted EBITDA	159.1			131.4			523.6	236.8
Adjusted EBITDA	159.1			131.4			523.6	236.8
All Other
Segment Reporting Information [Line Items]
Net revenue	26.2			13.4			53.2	26.4
Adjusted EBITDA	(3.0)			(9.5)			(23.6)	(29.5)
Adjusted EBITDA	(3.0)			(9.5)			(23.6)	(29.5)
Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue	81.5			71.1			336.7	130.5
Taxes and purses	(24.6)			(20.4)			(95.4)	(43.9)
Marketing and advertising	(2.9)			(2.7)			(9.9)	(4.2)
Salaries and benefits	(10.9)			(8.8)			(36.2)	(21.3)
Content expense	(0.5)			(0.2)			(1.9)	(1.0)
Selling, general and administrative expense	(3.1)			(2.8)			(9.2)	(5.7)
Other operating expense	(11.8)			(12.1)			(39.8)	(25.7)
Other income	0.0			0.0			0.1	0.0
Adjusted EBITDA	27.7			24.1			144.4	28.7
Asset impairments		$ 11.2
Adjusted EBITDA	27.7			24.1			144.4	28.7
Live and Historical Racing | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	79.7			63.8			318.8	115.2
Adjusted EBITDA	27.7			24.1			144.4	28.7
Adjusted EBITDA	27.7			24.1			144.4	28.7
TwinSpires
Segment Reporting Information [Line Items]
Net revenue	102.2			127.6			338.2	318.7
Taxes and purses	(8.0)			(8.2)			(22.7)	(19.2)
Marketing and advertising	(10.6)			(6.9)			(35.8)	(13.3)
Salaries and benefits	(3.6)			(3.1)			(9.9)	(9.6)
Content expense	(47.1)			(62.7)			(162.1)	(154.4)
Selling, general and administrative expense	(2.2)			(3.9)			(6.8)	(7.0)
Other operating expense	(10.0)			(10.2)			(34.6)	(28.0)
Other income	0.0			0.0			0.0	0.1
Adjusted EBITDA	20.7			32.6			66.3	87.3
Adjusted EBITDA	20.7			32.6			66.3	87.3
TwinSpires | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	101.8			127.1			337.1	317.5
Adjusted EBITDA	20.7			32.6			66.3	87.3
Adjusted EBITDA	20.7			32.6			66.3	87.3
Gaming
Segment Reporting Information [Line Items]
Net revenue	185.6			133.7			525.6	318.4
Taxes and purses	(71.8)			(51.5)			(201.1)	(124.5)
Marketing and advertising	(3.6)			(0.6)			(7.5)	(6.3)
Salaries and benefits	(22.5)			(19.1)			(63.0)	(57.6)
Content expense	(1.2)			(1.2)			(3.5)	(2.6)
Selling, general and administrative expense	(7.1)			(8.2)			(19.0)	(18.8)
Other operating expense	(19.7)			(14.3)			(52.9)	(44.8)
Other income	51.0			35.9			134.3	57.0
Adjusted EBITDA	110.7			74.7			312.9	120.8
Adjusted EBITDA	110.7			74.7			312.9	120.8
Gaming | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	185.3			133.5			523.3	316.7
Adjusted EBITDA	110.7			74.7			312.9	120.8
Adjusted EBITDA	$ 110.7			$ 74.7			$ 312.9	$ 120.8