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
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- Definition

Represents the taxes and surcharges on revenues from universal service funds (USF), which are included in operating revenues and expenses.

+ References

No definition available.

+ Details

Name:	ctl_UniversalServiceFundsTaxesAndSurcharges
Namespace Prefix:	ctl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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- 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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8933-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

+ Details

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

- Details

Name:	srt_ProductOrServiceAxis=ctl_IPDataServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ctl_TransportInfrastructureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ctl_VoiceCollaborationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ctl_ITManagedServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ctl_RegulatoryRevenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ctl_AffiliatesAndOtherServicesMember
Namespace Prefix:
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Products and Services Revenues (Details) $ in Millions	3 Months Ended								12 Months Ended
Products and Services Revenues (Details) $ in Millions	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) segment category	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Products and Services Revenues
Number of categories of products and services (categories) \| category									6
Operating revenue	$ 2,012	$ 2,039	$ 2,051	$ 2,055	$ 2,113	$ 2,149	$ 2,101	$ 2,130	$ 8,157	$ 8,493	$ 8,550
Taxes and surcharges included in operating revenues and expenses									$ 125	124	134
Number of reportable segments \| segment									1
IP and Data Services
Products and Services Revenues
Operating revenue									$ 624	615	634
Transport and Infrastructure
Products and Services Revenues
Operating revenue									2,829	2,925	3,006
Voice and Collaboration
Products and Services Revenues
Operating revenue									1,639	1,798	1,980
IT and Managed Services
Products and Services Revenues
Operating revenue									3	6	0
Regulatory Services
Products and Services Revenues
Operating revenue									189	214	211
Affiliate Services
Products and Services Revenues
Operating revenue									$ 2,873	$ 2,935	$ 2,719