The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

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Goodwill and Intangible Assets Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Jan. 24, 2013
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived	$ 0	$ 0
Gross Carrying Amount	21.9	21.9		21.9
Accumulated Amortization	(20.9)	(18.4)		(20.9)
Amortization of Intangible Assets	2.5us-gaap_AmortizationOfIntangibleAssets	3.6us-gaap_AmortizationOfIntangibleAssets	18.6us-gaap_AmortizationOfIntangibleAssets
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2015	0.8			0.8
2016	0.2			0.2
Data Center Colocation [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived			(1.5)
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	15.7	15.7		15.7
Accumulated Amortization	(15.2)	(14.6)		(15.2)
Customer Relationships [Member] \| Wireline [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	10 years
Gross Carrying Amount	7.0	7.0		7.0
Accumulated Amortization	(6.6)	(6.1)		(6.6)
Customer Relationships [Member] \| Wireless [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	9 years
Gross Carrying Amount	8.7	8.7		8.7
Accumulated Amortization	(8.6)	(8.5)		(8.6)
Customer Relationships [Member] \| Data Center Colocation [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net					91.7
Trademarks [Member] \| Wireless [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	6 years			30 months
Gross Carrying Amount	6.2	6.2		6.2
Accumulated Amortization	(5.7)	(3.8)		(5.7)
Trademarks [Member] \| Data Center Colocation [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net					6.1
Lease Agreements [Member] \| Data Center Colocation [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net					3.7
Licensing Agreements [Member]
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	$ 0	$ 88.2		$ 0