Segment Information - Schedule of Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net revenues	$ 178.9	$ 196.9	$ 339.3	$ 167.5	$ 161.8	$ 181.0	$ 313.3	$ 166.3	$ 882.6	$ 822.4	$ 798.6
Other operating expense									(1.5)	2.3	0.0
Adjusted EBITDA									366.5	334.5	302.5
Racing
Segment Reporting Information [Line Items]
Net revenues									257.3	251.1	248.0
Adjusted EBITDA									84.5	79.7	71.8
Casino
Segment Reporting Information [Line Items]
Net revenues									350.5	332.8	332.9
Adjusted EBITDA									146.0	125.8	114.9
TwinSpires
Segment Reporting Information [Line Items]
Net revenues									255.6	221.6	201.1
Adjusted EBITDA									64.4	56.2	49.5
Other Investments
Segment Reporting Information [Line Items]
Net revenues									19.2	16.9	16.6
Adjusted EBITDA									3.7	2.7	2.9
Corporate
Segment Reporting Information [Line Items]
Net revenues									0.0	0.0	0.0
Adjusted EBITDA									(12.4)	(12.1)	(8.1)
Operating Segments | Racing
Segment Reporting Information [Line Items]
Net revenues									276.6	268.1	262.2
Taxes & purses									(65.4)	(64.2)	(63.6)
Platform & development fees									0.0	0.0	0.0
Marketing & advertising									(4.9)	(4.6)	(6.1)
Salaries & benefits									(41.7)	(40.9)	(39.2)
Content expense									(15.2)	(15.6)	(14.6)
SG&A expense									(16.8)	(16.2)	(16.6)
Research & development									0.0	0.0	0.0
Other operating expense									(48.9)	(47.4)	(50.9)
Other income									0.8	0.5	0.6
Adjusted EBITDA									84.5	79.7	71.8
Operating Segments | Casino
Segment Reporting Information [Line Items]
Net revenues									350.5	332.8	332.9
Taxes & purses									(117.0)	(110.9)	(109.9)
Platform & development fees									0.0	0.0	0.0
Marketing & advertising									(12.1)	(12.7)	(12.4)
Salaries & benefits									(53.2)	(50.8)	(49.7)
Content expense									0.0	0.0	0.0
SG&A expense									(22.6)	(21.2)	(24.1)
Research & development									0.0	0.0	0.0
Other operating expense									(41.6)	(39.1)	(41.3)
Other income									42.0	27.7	19.4
Adjusted EBITDA									146.0	125.8	114.9
Operating Segments | TwinSpires
Segment Reporting Information [Line Items]
Net revenues									256.7	222.9	202.2
Taxes & purses									(14.7)	(11.6)	(10.6)
Platform & development fees									0.0	0.0	0.0
Marketing & advertising									(8.2)	(6.3)	(4.8)
Salaries & benefits									(9.9)	(9.4)	(9.9)
Content expense									(125.0)	(107.6)	(97.9)
SG&A expense									(12.4)	(12.0)	(11.5)
Research & development									0.0	0.0	0.0
Other operating expense									(22.1)	(19.8)	(18.0)
Other income									0.0	0.0	0.0
Adjusted EBITDA									64.4	56.2	49.5
Operating Segments | Other Investments
Segment Reporting Information [Line Items]
Net revenues									23.7	20.8	20.1
Taxes & purses									0.0	0.0	0.0
Platform & development fees									0.0	0.0	0.0
Marketing & advertising									0.0	0.0	0.0
Salaries & benefits									(12.0)	(10.9)	(11.1)
Content expense									0.0	0.0	0.0
SG&A expense									(3.3)	(3.4)	(2.5)
Research & development									0.0	0.0	0.0
Other operating expense									(5.1)	(4.1)	(3.8)
Other income									0.4	0.3	0.2
Adjusted EBITDA									3.7	2.7	2.9
Operating Segments | Corporate
Segment Reporting Information [Line Items]
Net revenues									0.0	0.0	0.0
Taxes & purses									0.0	0.0	0.0
Platform & development fees									0.0	0.0	0.0
Marketing & advertising									0.0	0.0	0.0
Salaries & benefits										0.0	0.0
Content expense									0.0	0.0	0.0
SG&A expense									(12.2)	(11.7)	(9.3)
Research & development									0.0	0.0	0.0
Other operating expense									(0.5)	(0.6)	1.1
Other income									0.3	0.2	0.1
Adjusted EBITDA									(12.4)	(12.1)	(8.1)
Discontinued Operations, Held-for-sale | Big Fish Games
Segment Reporting Information [Line Items]
Taxes & purses									0.0	0.0	0.0
Platform & development fees									(167.8)	(179.9)	(143.6)
Marketing & advertising									(116.6)	(127.9)	(107.7)
Salaries & benefits									(27.8)	(25.0)	(22.3)
Content expense									0.0	0.0	0.0
SG&A expense									(16.6)	(15.4)	(13.8)
Research & development									(39.6)	(39.0)	(39.4)
Other operating expense									(15.6)	(15.9)	(14.8)
Other income									(1.7)	(0.9)	(0.6)
Adjusted EBITDA									80.3	82.2	71.5
Discontinued Operations, Held-for-sale | Operating Segments | Big Fish Games
Segment Reporting Information [Line Items]
Net revenues									466.0	486.2	413.7
Big Fish Games | Discontinued Operations, Held-for-sale
Segment Reporting Information [Line Items]
Adjusted EBITDA									80.3	82.2	71.5
Adjusted EBITDA corporate and other expenses										3.1	3.0
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