Goodwill, Customer Relationships and Other Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014 segment	Dec. 31, 2013	Dec. 31, 2012
Finite and Indefinite-Lived Intangible Assets by Major Class [Line Items]
Goodwill	$ 9,354us-gaap_Goodwill	$ 9,354us-gaap_Goodwill
Finite-lived intangible assets, net	3,039us-gaap_FiniteLivedIntangibleAssetsNet	3,687us-gaap_FiniteLivedIntangibleAssetsNet
Gross carrying amounts of goodwill, customer relationships and other intangible assets	17,108
Amortization expense for intangible assets	957us-gaap_AmortizationOfIntangibleAssets	1,029us-gaap_AmortizationOfIntangibleAssets	1,115us-gaap_AmortizationOfIntangibleAssets
Number of reporting units (segment)	1us-gaap_NumberOfReportableSegments
Weighted average cost of capital to calculate discount rate as of the measurement date (as a percent)	6.00%us-gaap_FairValueInputsDiscountRate
Weighted average cost of capital, cost of equity (as a percent)	8.20%ctq_FairValueInputsCostOfEquityRate
Weighted average cost of capital, after-tax cost of debt (as a percent)	2.90%
Estimated amortization expense for intangible assets
2015	808
2016	740
2017	669
2018	589
2019	503
Customer relationships
Finite and Indefinite-Lived Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, net	3,039	3,687
Accumulated amortization	2,660	2,012
Capitalized software
Finite and Indefinite-Lived Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, net	808	1,008
Accumulated amortization	$ 1,247	$ 994

Represents the entity's cost of debt, expressed as a percentage, used as an input to measure fair value.

No definition available.

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- Definition

Represents the entity's cost of equity, expressed as a percentage, used as an input to measure fair value.

+ References

No definition available.

+ Details

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- Details

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- Definition

Amount before accumulated amortization of finite-lived intangible assets, indefinite-lived intangible assets and goodwill. Goodwill is an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Intangible assets are assets, not including financial assets, lacking physical substance.)

+ References

No definition available.

+ Details

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

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- Definition

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.

+ References