Segment Information - Reconciliation of Comprehensive Income to Adjusted EBITDA (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Comprehensive income	$ 140.4	$ 107.5	$ 64.7
Foreign currency translation, net of tax	0.1	(0.2)	0.5
Net change in pension benefits, net of tax	0.0	0.8	0.0
Net income	140.5	108.1	65.2
Depreciation and amortization	97.1	108.6	109.7
Loss on extinguishment of debt	20.7	0.0	0.0
Income tax (benefit) provision	(19.9)	50.7	44.6
EBITDA	292.8	320.4	250.4
Stock-based compensation expense	27.1	18.9	13.8
Impairment of tangible and other intangible assets	21.7	0.0	0.0
Calder exit costs	0.8	2.5	13.9
Total adjustments to EBITDA	73.7	14.1	52.1
Adjusted EBITDA	366.5	334.5	302.5
Racing
Segment Reporting Information [Line Items]
Adjusted EBITDA	84.5	79.7	71.8
Casino
Segment Reporting Information [Line Items]
Adjusted EBITDA	146.0	125.8	114.9
TwinSpires
Segment Reporting Information [Line Items]
Adjusted EBITDA	64.4	56.2	49.5
Other Investments
Segment Reporting Information [Line Items]
Adjusted EBITDA	3.7	2.7	2.9
Corporate
Segment Reporting Information [Line Items]
Adjusted EBITDA	(12.4)	(12.1)	(8.1)
Discontinued Operations, Held-for-sale | Big Fish Games
Segment Reporting Information [Line Items]
Adjusted EBITDA	80.3	82.2	71.5
Big Fish Games | Discontinued Operations, Held-for-sale
Segment Reporting Information [Line Items]
Adjusted EBITDA corporate and other expenses		3.1	3.0
Transaction expense, net	4.7	5.8	21.7
Adjusted EBITDA	80.3	82.2	71.5
Big Fish Games | Discontinued Operations, Held-for-sale | Corporate
Segment Reporting Information [Line Items]
Adjusted EBITDA corporate and other expenses	3.6	3.1	3.0
Continuing Operations
Segment Reporting Information [Line Items]
Depreciation and amortization	56.0	58.4	58.0
Interest expense	49.3	43.7	28.6
Loss on extinguishment of debt	20.7	0.0	0.0
Income tax (benefit) provision	(19.9)	50.7	44.6
Stock-based compensation expense	16.0	13.3	12.5
Other charges	1.2	2.5	0.0
Interest, depreciation and amortization expense related to equity investments	16.7	10.0	8.5
Other charges and recoveries, net	0.0	0.5	(5.8)
Impairment of tangible and other intangible assets	21.7	0.0	0.0
Gain on Calder land sale	0.0	(23.7)	0.0
Calder exit costs	0.8	2.5	13.9
Other, net	1.5	(2.4)	0.0
Discontinued Operations
Segment Reporting Information [Line Items]
Depreciation and amortization	41.1	50.2	51.7
Income tax (benefit) provision	5.1	9.3	2.3
Stock-based compensation expense	11.1	5.6	1.3
Transaction expense, net	$ 4.7	$ 5.8	$ 21.7