Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended					9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Jun. 30, 2014
Proceeds from Sale of Intangible Assets					$ 194.4
Disposal Group, Including Discontinued Operation, Intangible Assets, Noncurrent									$ 88.2
Prepaid Expense, Current	$ 15.0					$ 15.0		$ 13.1
Selling, general and administrative	55.5	$ 52.5				164.9	$ 161.7
Depreciation and amortization expense	46.5	35.8				134.7	102.4
Amortization of deferred gain						0.0	(6.5)
Operating income	25.5	36.2				82.5	103.0
Other (income) expense	0.1	(1.2)				1.2	(6.0)
Gain on transfer of tower lease obligations and other assets			$ 15.9			0.0	(15.9)
Gain on sale of wireless spectrum licenses						0.0	(112.6)
Income tax expense (benefit)	10.8	44.1				59.9	146.1
Net income	18.8	80.3				103.4	321.1
Restructuring liability	0.1					0.1		0.9
Other current liabilities from discontinued operations	0.4					0.4		5.4
Discontinued Operations [Member]
Prepaid Expense, Current					$ 6.4
Revenue		0.0					4.4
Cost of products and services		0.0					12.0
Selling, general and administrative		0.0					2.2
Depreciation and amortization expense		0.0				0.0	28.6
Restructuring charges		(2.1)					4.3
Amortization of deferred gain		0.0				0.0	(6.5)
Total operating costs and expenses		(2.1)					40.6
Operating income		2.1					(36.2)
Interest (income) expense		0.0					(1.7)
Other (income) expense		(0.1)					(0.2)
Gain on transfer of tower lease obligations and other assets		0.0				0.0	(15.9)
Gain on sale of wireless spectrum licenses		0.0		$ 112.6		0.0	112.6
Income (loss) before income taxes		2.2					94.2
Income tax expense (benefit)		1.2					33.4
Net income	0.0	$ 1.0				0.0	60.8
Restructuring liability	0.2					0.2		4.7
Other current liabilities from discontinued operations	0.2					0.2		0.7
Total current liabilities from discontinued operations	$ 0.4					0.4		$ 5.4
Non-cash spectrum lease						0.0	3.2
Restructuring payments						$ (4.2)	$ (11.2)