Business Segment Information (Details) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information, Additional Information [Abstract]
Number of Operating Segments					3
(Income) loss from CyrusOne equity method investment	$ 1.3	$ 2.4	$ 4.4	$ 1.9
Investment in CyrusOne	124.9		124.9		$ 273.6
Segment Reporting Information [Line Items]
Revenue	285.8	283.0	578.7	565.2
Operating income (loss)	29.7	47.3	66.8	97.7
Expenditures for long-lived assets	74.6	40.6	132.5	75.5
Depreciation and amortization	34.0	31.0	66.6	62.1
Assets	1,509.6		1,509.6		1,820.7
Entertainment and Communications [Member]
Segment Reporting Information [Line Items]
Revenue	182.4	184.7	370.5	368.3
Operating income (loss)	30.1	49.6	71.4	101.4
Expenditures for long-lived assets	70.1	38.1	124.1	64.3
Depreciation and amortization	31.0	28.2	60.5	56.3
Assets	911.5		911.5		833.2
IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	106.3	101.6	213.9	203.5
Operating income (loss)	6.2	2.8	7.3	8.2
Expenditures for long-lived assets	4.4	2.5	8.3	5.0
Depreciation and amortization	3.0	2.8	6.1	5.6
Assets	62.3		62.3		61.4
Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Assets	1.6		1.6		49.3
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	(6.6)	(5.1)	(11.9)	(11.9)
Expenditures for long-lived assets	0.1	0.0	0.1	0.0
Depreciation and amortization	0.0	0.0	0.0	0.2
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Revenue	(2.9)	(3.3)	(5.7)	(6.6)
Intersegment Elimination [Member] \| Entertainment and Communications [Member]
Segment Reporting Information [Line Items]
Revenue	0.4	0.3	0.7	0.5
Intersegment Elimination [Member] \| IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	2.5	3.0	5.0	6.1
Intersegment Elimination [Member] \| Corporate Segment [Member]
Segment Reporting Information [Line Items]
Assets	534.2		534.2		$ 876.8
Sales [Member] \| Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Revenue	$ 2.9	$ 3.3	$ 5.7	6.6
Continuing Operations [Member]
Segment Reporting Information [Line Items]
Expenditures for long-lived assets				$ 69.3

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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