Represents the period over which accounts receivable are outstanding for it to be considered as accounts past due.

No definition available.

Name:	ctl_AccountsReceivablePeriodPastDue
Namespace Prefix:	ctl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ctl_DistributionsPreferredStockAbstract
Namespace Prefix:	ctl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ctl_FiniteandIndefiniteLivedIntangibleAssetsbyMajorClassAbstract
Namespace Prefix:	ctl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the term of indefeasible rights of use commonly referred to as IRUs, which are the exclusive right to use a specified amount of capacity or fiber.

+ References

No definition available.

+ Details

Name:	ctl_IndefeasibleRightsOfUseTerm
Namespace Prefix:	ctl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Total preferential distribution available for each share of preferred stock.

+ References

No definition available.

+ Details

Name:	ctl_PreferentialPreferredStockDistribution
Namespace Prefix:	ctl_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the customer relationship period considered for recognition of revenue.

+ References

No definition available.

+ Details

Name:	ctl_RevenueRecognitionCustomerRelationshipPeriod
Namespace Prefix:	ctl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AccountsReceivableNetAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 720

-SubTopic 35

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848

+ Details

Name:	us-gaap_AdvertisingExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount before 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

Name:	us-gaap_FiniteLivedIntangibleAssetsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_MarketingAndAdvertisingExpenseAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RevenueRecognitionAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=ctl_IntegratedBillingandCustomerCareSystemMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_ComputerSoftwareIntangibleAssetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_OtherIntangibleAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
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Basis of Presentation and Summary of Significant Accounting Policies (Details 3) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue Recognition
Term of indefeasible rights of use (in years)	20 years
Advertising Costs
Advertising expense	$ 214us-gaap_AdvertisingExpense	$ 210us-gaap_AdvertisingExpense	$ 189us-gaap_AdvertisingExpense
Preferred stock
Preferential preferred stock distribution (in dollars per share)	$ 25
Minimum
Revenue Recognition
Customer relationship period for revenue recognition (from eighteen months to over ten years)	18 months
Accounts Receivable and Allowance for Doubtful Accounts
Period of accounts past due	30 days
Maximum
Revenue Recognition
Customer relationship period for revenue recognition (from eighteen months to over ten years)	10 years
Customer relationship \| Minimum
Goodwill and other intangible assets
Estimated useful life	10 years
Customer relationship \| Maximum
Goodwill and other intangible assets
Estimated useful life	15 years
Capitalized software \| Maximum
Goodwill and other intangible assets
Estimated useful life	7 years
Integrated billing and customer care system
Goodwill and other intangible assets
Estimated useful life	20 years
Finite-lived intangible assets, gross	$ 237
Other
Goodwill and other intangible assets
Estimated useful life	4 years