Segment Information - Information About Reported Segments (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) Segments	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)
Segment Reporting Information [Line Items]
Racing	$ 156.1	$ 155.4	$ 182.3	$ 179.2
Casinos	84.4	83.8	170.9	169.8
TwinSpires	68.2	60.7	117.6	106.1
Big Fish Games	125.2	104.5	247.3	196.4
Other Investments	4.4	4.5	8.4	8.1
Corporate	$ 0.2	0.3	0.4	0.5
Number of Operating Segments | Segments	6
Property, Plant and Equipment, Additions			34.5	22.7
Net revenue from external customers	$ 438.5	409.2	726.9	660.1
Intercompany net revenues	0.0	0.0	0.0	0.0
Total segment Adjusted EBITDA	162.9	158.9	215.7	208.7
Adjusted Corporate EBITDA	(1.9)	(1.7)	(3.9)	(3.6)
Change in Big Fish Games deferred revenue	(2.7)	(8.2)	(8.8)	(21.1)
Stock-based compensation expense	(5.3)	(3.4)	(9.4)	(6.1)
Other charges	(0.3)	0.0	(0.3)	0.0
Equity investments - interest, depreciation and amortization expense	(2.5)	(2.2)	(5.0)	(4.2)
Other (charges) and recoveries, net	0.0	0.0	(0.4)	6.1
Big Fish Games adjustments	(1.1)	(8.2)	(3.8)	(14.6)
Calder exit costs	(1.5)	(0.8)	(1.9)	(0.8)
Depreciation and amortization	(26.9)	(27.3)	(53.9)	(54.7)
Interest (expense) income, net	(11.1)	(7.1)	(21.7)	(14.4)
Income before income tax provision	111.5	101.7	110.5	98.9
Income tax provision	(41.7)	(46.6)	(37.9)	(45.4)
Net income	69.8	55.1	72.6	53.5
Foreign currency translation, net of tax	0.2	(0.1)	0.2	(0.4)
Comprehensive income	70.0	55.0	72.8	53.1
Racing Segment [Member]
Segment Reporting Information [Line Items]
Racing	156.1	155.4	182.3	179.2
Property, Plant and Equipment, Additions			20.8	6.6
Net revenue from external customers	164.7	162.2	193.2	188.1
Intercompany net revenues	8.6	6.8	10.9	8.9
Total segment Adjusted EBITDA	91.3	85.2	83.9	76.0
Racing Segment [Member] | Churchill Downs
Segment Reporting Information [Line Items]
Racing	129.1	126.8	131.4	128.8
Intercompany net revenues	7.0	5.4	7.3	5.6
Racing Segment [Member] | Arlington Park
Segment Reporting Information [Line Items]
Racing	16.8	18.1	25.8	23.9
Intercompany net revenues	1.6	1.4	2.6	2.4
Racing Segment [Member] | Fair Grounds
Segment Reporting Information [Line Items]
Racing	9.5	9.8	23.8	25.1
Intercompany net revenues	0.0	0.0	1.0	0.9
Racing Segment [Member] | Calder
Segment Reporting Information [Line Items]
Racing	0.7	0.7	1.3	1.4
Casino Segment [Member]
Segment Reporting Information [Line Items]
Casinos	84.4	83.8	170.9	169.8
Property, Plant and Equipment, Additions			6.8	11.4
Net revenue from external customers	84.4	83.8	170.9	169.8
Total segment Adjusted EBITDA	33.3	29.5	67.6	59.9
Casino Segment [Member] | Oxford Casino
Segment Reporting Information [Line Items]
Casinos	21.1	21.0	41.0	38.5
Casino Segment [Member] | Riverwalk Casino
Segment Reporting Information [Line Items]
Casinos	12.4	12.5	25.1	25.7
Casino Segment [Member] | Harlows Casino
Segment Reporting Information [Line Items]
Casinos	11.9	12.0	24.9	25.7
Casino Segment [Member] | Calder Casinos
Segment Reporting Information [Line Items]
Casinos	20.5	19.9	40.8	40.2
Casino Segment [Member] | Fair Grounds Slots
Segment Reporting Information [Line Items]
Casinos	8.8	9.0	19.4	21.1
Casino Segment [Member] | VSI
Segment Reporting Information [Line Items]
Casinos	9.5	9.4	19.3	18.6
Casino Segment [Member] | Saratoga Casino Holdings, LLC [Member]
Segment Reporting Information [Line Items]
Casinos	0.2	0.0	0.4	0.0
TwinSpires [Member]
Segment Reporting Information [Line Items]
TwinSpires	68.2	60.7	117.6	106.1
Property, Plant and Equipment, Additions			3.7	2.0
Net revenue from external customers	68.5	61.0	118.2	106.6
Intercompany net revenues	0.3	0.3	0.6	0.5
Total segment Adjusted EBITDA	18.4	16.1	30.5	26.2
Big Fish Games [Member]
Segment Reporting Information [Line Items]
Big Fish Games	125.2	104.5	247.3	196.4
Property, Plant and Equipment, Additions			2.2	1.9
Net revenue from external customers	125.2	104.5	247.3	196.4
Total segment Adjusted EBITDA	20.5	28.3	35.5	48.3
Other Investments Segment [Member]
Segment Reporting Information [Line Items]
Other Investments	4.4	4.5	8.4	8.1
Property, Plant and Equipment, Additions			0.4	0.3
Intercompany net revenues	1.4	1.1	2.3	1.9
Total segment Adjusted EBITDA	1.3	1.5	2.1	1.9
Corporate
Segment Reporting Information [Line Items]
Corporate	0.2	0.3	0.4	0.5
Property, Plant and Equipment, Additions			0.6	0.5
Net revenue from external customers	0.2	0.3	0.4	0.5
Total segment Adjusted EBITDA	(1.9)	(1.7)	(3.9)	(3.6)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intercompany net revenues	(10.3)	(8.2)	(13.8)	(11.3)
Social casino | Big Fish Games [Member]
Segment Reporting Information [Line Items]
Big Fish Games	46.5	48.4	94.0	98.0
Casual and mid-core free-to-play | Big Fish Games [Member]
Segment Reporting Information [Line Items]
Big Fish Games	56.0	32.4	106.4	53.9
Premium | Big Fish Games [Member]
Segment Reporting Information [Line Items]
Big Fish Games	24.6	28.3	51.3	58.3
Fair value adjustments | Big Fish Games [Member]
Segment Reporting Information [Line Items]
Big Fish Games	$ (1.9)	$ (4.6)	$ (4.4)	$ (13.8)