Represents the number of categories in which the entity categorizes the products and services.

No definition available.

Name:	ctl_NumberOfCategoriesOfProductsAndServices
Namespace Prefix:	ctl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of categories of products and services of the reporting entity that are included in segment revenue.

+ References

No definition available.

+ Details

Name:	ctl_NumberofCategoriesofProductsandServicesIncludedinSegmentRevenue
Namespace Prefix:	ctl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the universal taxes and surcharges that are reflected in the statement of income (included in both operating revenues and expenses).

+ References

No definition available.

+ Details

Name:	ctl_UniversalServiceTaxesAndSurcharges
Namespace Prefix:	ctl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

+ Details

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_ProductOrServiceAxis=ctl_DataIntegrationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=ctl_LegacyServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=ctl_OtherServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=ctl_StrategicServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Segment Information (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 category	Dec. 31, 2013	Dec. 31, 2012
Operating revenues by products and services
Operating revenues	$ 4,438us-gaap_Revenues	$ 4,514us-gaap_Revenues	$ 4,541us-gaap_Revenues	$ 4,538us-gaap_Revenues	$ 4,542us-gaap_Revenues	$ 4,515us-gaap_Revenues	$ 4,525us-gaap_Revenues	$ 4,513us-gaap_Revenues	$ 18,031us-gaap_Revenues	$ 18,095us-gaap_Revenues	$ 18,376us-gaap_Revenues
Surcharge amount on customers' bills									526ctl_UniversalServiceTaxesAndSurcharges	489ctl_UniversalServiceTaxesAndSurcharges	531ctl_UniversalServiceTaxesAndSurcharges
Number of categories of products and services (categories)									4
Number of categories of products and services included in segment revenue (categories)									3
Strategic services
Operating revenues by products and services
Operating revenues									9,200	8,823	8,427
Legacy services
Operating revenues by products and services
Operating revenues									7,138	7,616	8,221
Data integration
Operating revenues by products and services
Operating revenues									690	656	672
Other
Operating revenues by products and services
Operating revenues									$ 1,003	$ 1,000	$ 1,056