Segment Information - Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Net revenue	$ 324.3	$ 252.9
Net income (loss) and comprehensive income (loss) attributable to Churchill Downs Incorporated	36.1	(23.4)
Net loss attributable to noncontrolling interest	0.0	0.1
Net income (loss)	36.1	(23.5)
Loss from discontinued operations, net of tax	0.0	0.9
Income (loss) from continuing operations, net of tax	36.1	(22.6)
Depreciation and amortization	26.0	22.0
Interest expense	19.4	19.3
Income tax provision (benefit)	16.2	(11.6)
EBITDA	97.7	7.1
Stock-based compensation expense	5.5	4.3
Pre-opening expense and other expense	0.6	1.7
Impairment of intangible assets	0.0	17.5
Transaction expense, net	0.1	0.3
Interest, depreciation and amortization expense related to equity investments	9.6	9.5
Changes in fair value of Rivers Des Plaines' interest rate swaps	(4.2)	14.9
Rivers Des Plaines' legal reserves and transaction costs	1.3	0.0
Total adjustments to EBITDA	12.9	48.2
Adjusted EBITDA	110.6	55.3
Operating Segments
Segment Reporting Information [Line Items]
Net revenue	324.3	252.9
Adjusted EBITDA	123.2	64.9
Segment Reconciling Items
Segment Reporting Information [Line Items]
Net revenue	9.4	9.8
Adjusted EBITDA	(12.6)	(9.6)
Live and Historical Racing
Segment Reporting Information [Line Items]
Net revenue	64.7	29.1
Adjusted EBITDA	18.3	1.0
Live and Historical Racing | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	63.2	28.1
Taxes and purses	(20.0)	(9.5)
Marketing and advertising	(2.1)	(1.2)
Salaries and benefits	(10.0)	(7.2)
Content expense	(0.6)	(0.7)
Selling, general and administrative expense	(3.0)	(1.7)
Other operating expense	(10.7)	(7.8)
Other income	0.0	0.0
Adjusted EBITDA	18.3	1.0
TwinSpires
Segment Reporting Information [Line Items]
Net revenue	100.1	69.4
Adjusted EBITDA	22.5	16.0
TwinSpires | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	99.7	69.1
Taxes and purses	(6.4)	(4.3)
Marketing and advertising	(8.5)	(3.5)
Salaries and benefits	(3.1)	(3.5)
Content expense	(46.5)	(32.6)
Selling, general and administrative expense	(2.2)	(1.4)
Other operating expense	(10.9)	(8.1)
Other income	0.0	0.0
Adjusted EBITDA	22.5	16.0
Gaming
Segment Reporting Information [Line Items]
Net revenue	154.0	147.4
Adjusted EBITDA	82.4	47.9
Gaming | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	152.0	145.9
Taxes and purses	(59.3)	(58.7)
Marketing and advertising	(1.4)	(5.3)
Salaries and benefits	(19.9)	(29.5)
Content expense	(1.0)	(1.0)
Selling, general and administrative expense	(6.0)	(6.7)
Other operating expense	(15.5)	(19.5)
Other income	31.5	21.2
Adjusted EBITDA	$ 82.4	$ 47.9