Segment Information - Reconciliation of Comprehensive Income to Adjusted EBITDA (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Comprehensive income	$ 107.5	$ 64.7	$ 46.3
Foreign currency translation, net of tax	(0.2)	0.5	0.1
Net change in pension benefits, net of tax	0.8	0.0	0.0
Net income	108.1	65.2	46.4
Depreciation and amortization	108.6	109.7	68.3
Interest expense	43.7	28.6	20.8
Income tax provision	60.0	46.9	30.1
EBITDA	320.4	250.4	165.6
Stock-based compensation expense	18.9	13.8	11.9
Other charges	2.5	0.0	(0.4)
Segment Operating Expense	0.0	0.0	3.2
Interest, depreciation and amortization expense related to equity investments	10.0	8.5	8.7
Other charges and recoveries, net	0.5	(5.8)	2.6
Acquisition expense, net	3.4	21.7	10.2
Gain on Calder land sale	(23.7)	0.0	0.0
Calder exit costs	2.5	13.9	2.3
Total adjustments to EBITDA	14.1	52.1	38.5
Adjusted EBITDA	334.5	302.5	204.1
Racing
Segment Reporting Information [Line Items]
Adjusted EBITDA	79.7	71.8	61.2
Casinos
Segment Reporting Information [Line Items]
Adjusted EBITDA	125.8	114.9	107.2
TwinSpires
Segment Reporting Information [Line Items]
Adjusted EBITDA	55.2	48.6	39.8
Big Fish Games
Segment Reporting Information [Line Items]
Adjusted EBITDA	79.1	68.5	(0.7)
Other Investments
Segment Reporting Information [Line Items]
Adjusted EBITDA	2.7	2.9	1.6
Corporate
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ (8.0)	$ (4.2)	$ (5.0)