Segment Information Adjusted EBITDA by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Net revenue from external customers	$ 451.9	$ 438.5	$ 731.4	$ 726.9
Research & development	(9.9)	(9.7)	(20.2)	(20.5)
Adjusted EBITDA	173.0	160.2	230.3	206.9
Racing Segment [Member]
Segment Reporting Information [Line Items]
Net revenue from external customers	175.7	164.7	201.8	193.2
Taxes & purses	(32.9)	(30.3)	(43.1)	(41.5)
Platform & development fees	0.0	0.0	0.0	0.0
Marketing & advertising	(2.2)	(1.9)	(2.9)	(2.7)
Salaries & benefits	(13.5)	(12.7)	(22.1)	(21.1)
Content expense	(4.7)	(4.8)	(7.9)	(8.1)
SG&A expense	(4.2)	(4.0)	(8.0)	(7.9)
Research & development	0.0	0.0	0.0	0.0
Other operating expense	20.0	19.9	29.3	28.3
Other income (expense)	0.5	0.2	0.5	0.3
Adjusted EBITDA	98.7	91.3	89.0	83.9
Casino Segment [Member]
Segment Reporting Information [Line Items]
Net revenue from external customers	88.3	84.4	175.8	170.9
Taxes & purses	(29.7)	(28.1)	(58.8)	(56.5)
Platform & development fees	0.0	0.0	0.0	0.0
Marketing & advertising	(3.0)	(3.1)	(6.0)	(6.5)
Salaries & benefits	(13.4)	(12.7)	(26.5)	(24.8)
Content expense	0.0	0.0	0.0	0.0
SG&A expense	(5.6)	(5.3)	(10.8)	(10.4)
Research & development	0.0	0.0	0.0	0.0
Other operating expense	9.8	9.7	21.2	19.4
Other income (expense)	10.7	7.8	20.3	14.3
Adjusted EBITDA	37.5	33.3	72.8	67.6
TwinSpires [Member]
Segment Reporting Information [Line Items]
Net revenue from external customers	80.8	68.7	133.1	118.6
Taxes & purses	(4.1)	(2.0)	(7.1)	(4.8)
Platform & development fees	0.0	0.0	0.0	0.0
Marketing & advertising	(4.6)	(3.2)	(5.6)	(4.2)
Salaries & benefits	(2.6)	(2.3)	(4.8)	(4.6)
Content expense	(40.2)	(33.5)	(65.6)	(57.4)
SG&A expense	(3.0)	(2.8)	(5.7)	(5.6)
Research & development	0.0	0.0	0.0	0.0
Other operating expense	7.0	6.1	11.8	11.1
Other income (expense)	0.0	0.0	0.0	0.0
Adjusted EBITDA	19.3	18.8	32.5	30.9
Big Fish Games [Member]
Segment Reporting Information [Line Items]
Net revenue from external customers	112.6	125.2	224.6	247.3
Taxes & purses	0.0	0.0	0.0	0.0
Platform & development fees	(40.4)	(45.9)	(81.9)	(90.0)
Marketing & advertising	(28.0)	(37.1)	(52.5)	(79.9)
Salaries & benefits	(6.9)	(6.1)	(13.9)	(12.2)
Content expense	0.0	0.0	0.0	0.0
SG&A expense	(5.1)	(4.3)	(9.8)	(9.2)
Research & development	(9.9)	(9.7)	(20.2)	(20.5)
Other operating expense	3.6	4.0	7.3	7.9
Other income (expense)	(0.4)	(0.3)	(0.4)	(0.9)
Adjusted EBITDA	18.3	17.8	38.6	26.7
Other Segments [Member]
Segment Reporting Information [Line Items]
Net revenue from external customers	6.5	5.8	12.0	10.7
Taxes & purses	0.0	0.0	0.0	0.0
Platform & development fees	0.0	0.0	0.0	0.0
Marketing & advertising	0.0	0.0	0.0	0.0
Salaries & benefits	(3.3)	(2.8)	(6.2)	(5.5)
Content expense	0.0	0.0	0.0	0.0
SG&A expense	(0.7)	(0.9)	(1.5)	(1.6)
Research & development	0.0	0.0		0.0
Other operating expense	1.2	1.0	2.5	1.7
Other income (expense)	0.0	0.2	0.1	0.2
Adjusted EBITDA	1.3	1.3	1.9	2.1
Corporate
Segment Reporting Information [Line Items]
Net revenue from external customers	0.0	0.0	0.0	0.0
Taxes & purses	0.0	0.0	0.0	0.0
Platform & development fees	0.0	0.0	0.0	0.0
Marketing & advertising	0.0	0.0	0.0	0.0
Salaries & benefits	0.0	0.0	0.0	0.0
Content expense	0.0	0.0	0.0	0.0
SG&A expense	(1.8)	(2.2)	(4.0)	(4.0)
Research & development	0.0	0.0	0.0	0.0
Other operating expense	0.3	0.0	0.5	0.3
Other income (expense)	0.0	(0.1)	0.0	0.0
Adjusted EBITDA	$ (2.1)	$ (2.3)	$ (4.5)	$ (4.3)