Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended									12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Selected Quarterly Financial Information [Abstract]
Revenue	$ 289.3	$ 299.8	$ 285.8	$ 292.9	$ 294.9	$ 301.4	$ 283.0	$ 282.2		$ 1,167.8	$ 1,161.5	$ 1,073.4
Operating income	25.0	36.2	29.7	37.1	31.4	47.8	47.3	50.4		128.0	176.9	139.8
Income (Loss) from Continuing Operations Attributable to Parent	30.5	79.3	180.7	0.3	(4.4)	(7.5)	123.7	5.9		290.8	117.7	(64.9)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	2.1	1.0	10.9	48.9	(13.9)	(19.8)	(9.5)	1.1		62.9	(42.1)	10.2
Net income (loss)	$ 32.6	$ 80.3	$ 191.6	$ 49.2	$ (18.3)	$ (27.3)	$ 114.2	$ 7.0		$ 353.7	$ 75.6	$ (54.7)
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.13	$ 0.37	$ 0.85	$ (0.01)	$ (0.03)	$ (0.05)	$ 0.58	$ 0.02		$ 1.34	$ 0.51	$ (0.37)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0.01	0.00	0.05	0.23	(0.07)	(0.09)	(0.04)	0.00		0.30	(0.20)	0.05
Earnings Per Share, Basic	0.14	0.37	0.90	0.22	(0.10)	(0.14)	0.54	0.02		1.64	0.31	(0.32)
Income (Loss) from Continuing Operations, Per Diluted Share	0.13	0.37	0.84	(0.01)	(0.03)	(0.05)	0.58	0.02		1.33	0.51	(0.37)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0.01	0.00	0.05	0.23	(0.07)	(0.09)	(0.05)	0.00		0.30	(0.20)	0.05
Earnings Per Share, Diluted	$ 0.14	$ 0.37	$ 0.89	$ 0.22	$ (0.10)	$ (0.14)	$ 0.53	$ 0.02		$ 1.63	$ 0.31	$ (0.32)
Effect of Fourth Quarter Events [Line Items]
Gain on sale of CyrusOne equity method investment	$ 36.3	$ 117.7	$ 295.2				$ 192.8			$ 449.2	$ 192.8	$ 0.0
Impairment of assets, excluding goodwill										0.0	(4.6)	0.0
Gains (Losses) on Extinguishment of Debt										20.9	19.6	29.6
Gain (Loss) on Disposition of Intangible Assets				$ 112.6						112.6	0.0	0.0
Gain on Liabilities and Other Assets transferred in Sale of Business Affiliate and Productive Assets			15.9							15.9	0.0	0.0
Senior Subordinated Notes due 2018 [Member]
Effect of Fourth Quarter Events [Line Items]
Extinguishment of Debt, Amount			$ 300.0			$ 325.0
Debt Instrument, Redemption Price, Percentage			102.188%			104.375%
Gains (Losses) on Extinguishment of Debt			$ (10.4)			$ (19.4)
Senior Notes due 2020 [Member]
Effect of Fourth Quarter Events [Line Items]
Extinguishment of Debt, Amount		$ 137.6	$ 45.1		$ 22.7					$ 182.7
Debt Instrument, Redemption Price, Percentage		105.242%	106.45%							105.543%
Gains (Losses) on Extinguishment of Debt		$ (7.8)	$ (3.1)							$ (10.9)
Senior Notes due 2017 [Member]
Effect of Fourth Quarter Events [Line Items]
Extinguishment of Debt, Amount												500.0
Debt Instrument, Redemption Price, Percentage									104.125%
Gains (Losses) on Extinguishment of Debt												29.6
Entertainment and Communications [Member]
Selected Quarterly Financial Information [Abstract]
Revenue										743.7	740.7	724.8
Operating income										$ 129.9	178.9	$ 186.2
Effect of Fourth Quarter Events [Line Items]
Impairment of assets, excluding goodwill											$ 4.6