Financial Instruments and Fair Value Measurements Non-Recurring Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of Intangible Assets, Finite-lived	$ 0	$ 0
Impairment of assets, excluding goodwill	12.1	0	14.2
Impairment of assets, excluding goodwill	(12.1)	0	(14.2)
Fair Value Inputs, Discount Rate			12.00%
Data Center Colocation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of Intangible Assets, Finite-lived			(1.5)
Impairment of assets, excluding goodwill			(11.8)
Impairment of assets, excluding goodwill			(13.3)
Property, Plant and Equipment at Carrying Value for Fair Value Measurement				14.2
Wireline [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of assets, excluding goodwill	(4.6)	0	(0.5)
Wireless [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of assets, excluding goodwill	(7.5)		(0.4)
Fair Value, Measurements, Nonrecurring [Member] | Data Center Colocation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure			2.8
Fair Value, Measurements, Nonrecurring [Member] | Wireless [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure			0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Data Center Colocation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure			0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Wireless [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure			0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Data Center Colocation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure			0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Wireless [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure			0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Data Center Colocation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure			2.8
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Wireless [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure			0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Wireline [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Wireless [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Wireline [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Wireless [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Wireline [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Wireless [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Wireline [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Wireless [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	0
Leasehold Improvements [Member] | Fair Value, Measurements, Nonrecurring [Member] | Data Center Colocation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure			2.4
Leasehold Improvements [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Data Center Colocation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure			0
Leasehold Improvements [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Data Center Colocation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure			0
Leasehold Improvements [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Data Center Colocation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure			2.4
Network Equipment [Member] | Fair Value, Measurements, Nonrecurring [Member] | Wireline [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure			0.4
Network Equipment [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Wireline [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure			0
Network Equipment [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Wireline [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure			0
Network Equipment [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Wireline [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure			$ 0.4