Name:	ctl_AcquireeStockholdersPercentageOwnershipInParentCompany
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Represents the percentage ownership of the Parent Company that will be held by the Parent Company's stockholders estimated based on the number of shares outstanding as of the date of closing.

No definition available.

Name:	ctl_AcquirorStockholdersPercentageOwnershipInParentCompany
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Data Type:	num:percentItemType
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Period Type:	instant

Represents the cash consideration per share to be paid to the acquired entity's stockholders in a proposed business acquisition.

No definition available.

Name:	ctl_BusinessAcquisitionCashPaymentToAcquireesShareholdersPerShare
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Data Type:	num:perShareItemType
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Period Type:	instant

Represents the amount of the Company's common stock that stockholders of the Acquiree will receive in exchange for each share of the Acquiree's common stock owned at closing.

No definition available.

Name:	ctl_CompanySharesExchangedforEachAcquireeShare
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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

The amount of fees paid by an entity to terminate a contractual agreement.

No definition available.

Name:	ctl_ContractTerminationFees
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Balance Type:	debit
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Represents the number of data centers owned by the Company.

No definition available.

Name:	ctl_NumberofDataCenters
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Balance Type:	na
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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6455398&loc=d3e45280-112737

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Name:	us-gaap_DebtAndCapitalLeaseObligations
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of revenue attributable to disposal group, including, but not limited to, discontinued operation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.

Name:	us-gaap_SubsequentEventLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	dei_LegalEntityAxis=ctl_Level3CommunicationsInc.Member
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Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=ctl_DataCentersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_BusinessAcquisitionAxis=ctl_Level3CommunicationsInc.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: