Discontinued Operations (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	Jun. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of intangible assets													$ 194.4
Disposal Group, Including Discontinued Operation, Intangible Assets, Noncurrent															$ 88.2
Prepaid Expense, Current	$ 22.2				$ 15.0					$ 22.2	$ 15.0			$ 6.4
Deferred gain on sale of wireless spectrum licenses - discontinued operations										0.0	0.0	$ (112.6)
Gain on Liabilities and Other Assets transferred in Sale of Business Affiliate and Productive Assets									$ (15.9)	0.0	0.0	(15.9)
Revenue, Net	427.1	$ 289.2	$ 294.0	$ 278.2	285.3	$ 312.4	$ 299.2	$ 288.9		1,288.5	1,185.8	1,167.8
Selling, General and Administrative Expense										240.9	218.7	219.1
Depreciation and amortization										193.0	182.2	141.6
Impairment of assets										0.0	0.0	0.0
Costs and Expenses										1,250.4	1,092.8	1,039.8
Operating (loss) income	$ 9.8	$ 12.7	$ 20.9	$ (5.3)	10.5	25.5	27.4	29.6		38.1	93.0	128.0
Other expense (income), net										1.4	(7.6)	2.6
Income tax expense (benefit)										30.9	61.1	159.8
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent					$ 0.3	$ 0.0	$ 0.0	$ 0.0		0.0	0.3	62.9
Repayment of debt										(403.0)	(759.3)	(531.7)
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred gain on sale of wireless spectrum licenses - discontinued operations										0.0	0.0	(112.6)
Gain on Liabilities and Other Assets transferred in Sale of Business Affiliate and Productive Assets										0.0	0.0	(15.9)
Revenue, Net										0.0	0.0	4.4
Cost of Goods and Services Sold										0.0	0.0	12.0
Selling, General and Administrative Expense										0.0	0.0	2.2
Depreciation and amortization										0.0	0.0	28.6
Restructuring charges										0.0	0.0	3.3
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property										0.0	0.0	(0.4)
Amortization of Deferred (Gain) Loss										0.0	0.0	(6.5)
Costs and Expenses										0.0	0.0	39.2
Operating (loss) income										0.0	0.0	(34.8)
Interest Income (Expense), Net										0.0	0.0	(1.7)
Other expense (income), net										0.0	(0.3)	(2.3)
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax										0.0	0.3	97.7
Income tax expense (benefit)										0.0	0.0	34.8
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent										0.0	0.3	62.9
Non-cash spectrum lease										0.0	0.0	3.2
Payments for Restructuring										0.0	(4.4)	(14.5)
Repayment of debt										$ 0.0	$ 0.0	$ (0.3)