Condensed Consolidated Statements Of Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net revenue:
Racing	$ 182.5	$ 165.3	$ 206.2	$ 189.2
TwinSpires	93.7	80.5	156.9	132.5
Casino	98.2	88.3	196.3	175.8
Other Investments	5.0	5.2	9.3	9.3
Total net revenue	379.4	339.3	568.7	506.8
Operating expense:
Racing	85.3	76.5	121.2	112.9
TwinSpires	59.4	51.4	103.4	87.8
Casino	67.3	62.1	132.1	124.8
Other Investments	5.0	4.9	9.6	8.8
Corporate	0.6	0.6	1.1	1.2
Selling, general and administrative expense	23.1	20.2	41.5	38.8
Calder exit costs	0.0	0.2	0.0	0.6
Transaction expense, net	2.1	0.5	3.5	0.5
Total operating expense	242.8	216.4	412.4	375.4
Operating income	136.6	122.9	156.3	131.4
Other income (expense):
Interest expense, net	(9.7)	(11.6)	(19.3)	(23.4)
Equity in income of unconsolidated investments	8.8	7.7	15.3	13.8
Miscellaneous, net	0.3	0.7	0.4	0.7
Total other expense	(0.6)	(3.2)	(3.6)	(8.9)
Income (loss) from operations before provision for income taxes	136.0	119.7	152.7	122.5
Income tax provision	(32.8)	(47.0)	(35.4)	(47.6)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	103.2	72.7	117.3	74.9
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	(0.1)	5.6	167.8	10.7
Net income	$ 103.1	$ 78.3	$ 285.1	$ 85.6
Net earnings per common share data:
Income (Loss) from Continuing Operations, Per Basic Share	$ 7.61	$ 4.52	$ 8.38	$ 4.62
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	(0.01)	0.34	11.98	0.65
Diluted	7.60	4.86	20.36	5.27
Income (Loss) from Continuing Operations, Per Diluted Share	7.57	4.47	8.34	4.53
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share	(0.02)	0.34	11.92	0.65
Earnings Per Share, Diluted [Abstract]
Diluted	$ 7.55	$ 4.81	$ 20.26	$ 5.18
Weighted average shares outstanding:
Numerator for diluted net income per common share:	13.5	16.1	14.0	16.2
Diluted (in shares)	13.6	16.3	14.1	16.5
Other comprehensive loss:
Foreign currency translation, net of tax	$ 0.0	$ (0.3)	$ 0.0	$ (0.4)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Noncontrolling Interest	(0.2)	0.0	(0.2)	0.0
Other comprehensive loss	(0.2)	(0.3)	(0.2)	(0.4)
Comprehensive income	$ 102.9	$ 78.0	$ 284.9	$ 85.2