Segment Information - Information About Reported Segments (Details)		3 Months Ended		9 Months Ended
	Aug. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) Segments	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | Segments		3
Net revenue		$ 306,300,000	$ 221,300,000	$ 1,049,100,000	$ 790,000,000.0
Intercompany net revenues		0	0	0	0
Comprehensive income		14,800,000	56,500,000	133,500,000	341,800,000
Foreign currency translation, net of tax		0	0	0	(600,000)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Noncontrolling Interest		0	(200,000)	0	200,000
Net income		14,800,000	56,300,000	133,500,000	341,400,000
Loss (income) from discontinued operations, net of tax		400,000	1,700,000	1,900,000	(166,100,000)
Income from continuing operations, net of tax		15,200,000	58,000,000.0	135,400,000	175,300,000
Depreciation and amortization		22,000,000.0	16,700,000	64,300,000	45,800,000
Interest expense		18,900,000	9,900,000	52,000,000.0	29,200,000
Income tax provision		8,000,000.0	16,700,000	53,100,000	52,100,000
EBITDA		64,100,000	101,300,000	304,800,000	302,400,000
Stock-based compensation expense		5,500,000	3,900,000	17,600,000	13,100,000
Legal reserves		3,300,000	0	3,600,000	0
Pre-opening expense and other expense		1,200,000	2,800,000	3,600,000	4,100,000
Gain on Ocean Downs/Saratoga transaction	$ 54,900,000	0	54,900,000	0	54,900,000
Interest, depreciation and amortization expense related to equity investments		9,700,000	3,600,000	22,900,000	12,200,000
Fair Value of Interest Rate Swaps		3,200,000	0	15,400,000	0
Midwest Gaming's recapitalization and transactions costs		0	0	4,700,000	0
Other charges & recoveries, net		100,000	0	0	0
Transaction expense, net		900,000	5,400,000	5,000,000.0	8,900,000
Total adjustments to EBITDA		23,900,000	(39,200,000)	72,800,000	(16,600,000)
Adjusted EBITDA		88,000,000.0	62,100,000	377,600,000	285,800,000
Disclosure of Complimentary Revenue		8,900,000	6,600,000	24,700,000	19,500,000
Churchill Downs
Segment Reporting Information [Line Items]
Net revenue		32,700,000	11,800,000	247,200,000	178,400,000
Adjusted Segment EBITDA		5,200,000	(2,800,000)	128,500,000	99,100,000
Online Wagering
Segment Reporting Information [Line Items]
Net revenue		70,400,000	72,100,000	229,800,000	229,800,000
Adjusted Segment EBITDA		15,000,000.0	20,800,000	54,100,000	63,100,000
Gaming
Segment Reporting Information [Line Items]
Net revenue		178,600,000	110,500,000	526,500,000	331,200,000
Adjusted Segment EBITDA		71,700,000	44,700,000	212,600,000	136,800,000
Operating Segments
Segment Reporting Information [Line Items]
Net revenue		306,300,000	221,300,000	1,049,100,000	790,000,000.0
Adjusted Segment EBITDA		91,900,000	62,700,000	395,200,000	299,000,000.0
Operating Segments | Churchill Downs
Segment Reporting Information [Line Items]
Net revenue		31,400,000	10,800,000	234,600,000	167,700,000
Intercompany net revenues		1,300,000	1,000,000.0	12,600,000	10,700,000
Adjusted Segment EBITDA		5,200,000	(2,800,000)	128,500,000	99,100,000
Operating Segments | Churchill Downs | Churchill Downs Racetrack
Segment Reporting Information [Line Items]
Net revenue		8,900,000	8,500,000	172,200,000	165,400,000
Operating Segments | Churchill Downs | Derby City Gaming
Segment Reporting Information [Line Items]
Net revenue		22,500,000	2,300,000	62,400,000	2,300,000
Operating Segments | Online Wagering
Segment Reporting Information [Line Items]
Net revenue		70,200,000	71,800,000	228,900,000	228,700,000
Intercompany net revenues		200,000	300,000	900,000	1,100,000
Adjusted Segment EBITDA		15,000,000.0	20,800,000	54,100,000	63,100,000
Operating Segments | Online Wagering | TwinSpires
Segment Reporting Information [Line Items]
Net revenue		70,300,000	71,800,000	228,800,000	228,700,000
Operating Segments | Online Wagering | Online Sports Betting and iGaming
Segment Reporting Information [Line Items]
Net revenue		(100,000)	0	100,000	0
Operating Segments | Gaming
Segment Reporting Information [Line Items]
Net revenue		178,300,000	110,400,000	524,700,000	330,000,000.0
Intercompany net revenues		300,000	100,000	1,800,000	1,200,000
Adjusted Segment EBITDA		71,700,000	44,700,000	212,600,000	136,800,000
Operating Segments | Gaming | Oxford Acquisition [Member]
Segment Reporting Information [Line Items]
Net revenue		27,200,000	28,900,000	77,400,000	79,300,000
Operating Segments | Gaming | Calder Casinos [Member]
Segment Reporting Information [Line Items]
Net revenue		24,400,000	24,000,000.0	75,400,000	74,900,000
Operating Segments | Gaming | Riverwalk
Segment Reporting Information [Line Items]
Net revenue		13,600,000	12,800,000	44,100,000	40,800,000
Operating Segments | Gaming | Harlow’s
Segment Reporting Information [Line Items]
Net revenue		13,300,000	12,100,000	41,900,000	37,900,000
Operating Segments | Gaming | Fair Grounds Slots [Member]
Segment Reporting Information [Line Items]
Net revenue		25,000,000.0	24,500,000	93,400,000	88,400,000
Operating Segments | Gaming | Ocean Downs LLC and Racing Services LLC [Member]
Segment Reporting Information [Line Items]
Net revenue		26,700,000	8,100,000	67,000,000.0	8,100,000
Operating Segments | Gaming | Presque Isle Downs & Casino [Member]
Segment Reporting Information [Line Items]
Net revenue		38,100,000	0	104,900,000	0
Operating Segments | Gaming | Lady Luck Nemacolin
Segment Reporting Information [Line Items]
Net revenue		10,000,000.0	0	20,600,000	0
Operating Segments | Gaming | Saratoga
Segment Reporting Information [Line Items]
Net revenue		0	0	0	600,000
Segment Reconciling Items | All Other
Segment Reporting Information [Line Items]
Net revenue		26,400,000	28,300,000	60,900,000	63,600,000
Intercompany net revenues		3,400,000	3,200,000	9,000,000.0	9,200,000
Adjusted Segment EBITDA		(3,900,000)	(600,000)	(17,600,000)	(13,200,000)
Eliminations
Segment Reporting Information [Line Items]
Intercompany net revenues		$ (5,200,000)	$ (4,600,000)	$ (24,300,000)	$ (22,200,000)