Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: 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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

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

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

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

- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

No definition available.

+ Details

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

- Details

Name:	dei_LegalEntityAxis=ctl_EmbarqMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	dei_LegalEntityAxis=ctl_QwestCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=ctl_A6.5Notesdue2017Member
Namespace Prefix:
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Balance Type:
Period Type:

- Details

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- Details

Name:	dei_LegalEntityAxis=us-gaap_ParentCompanyMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_DebtInstrumentAxis=ctl_A6.00Noteddue2017Member
Namespace Prefix:
Data Type:	na
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Long-Term Debt and Credit Facilities (Details 2) - Senior notes - USD ($) $ in Millions	Apr. 28, 2017	May 04, 2017	Apr. 03, 2017	Mar. 31, 2017
Embarq Corporation
Long-term Debt and Credit Facilities
Stated interest rate (percent)				7.995%
Subsequent event \| Qwest Corporation \| 6.5% Notes due 2017
Long-term Debt and Credit Facilities
Debt instrument, repurchased face amount		$ 500
Stated interest rate (percent)		6.50%
Subsequent event \| Qwest Corporation \| 6.75% Notes due 2057
Long-term Debt and Credit Facilities
Stated interest rate (percent)	6.75%
Debt instrument, face amount	$ 575
Proceeds from debt, net of issuance costs	$ 555
Subsequent event \| CenturyLink, Inc. \| 6.00% Noted due 2017
Long-term Debt and Credit Facilities
Debt instrument, repurchased face amount			$ 500
Stated interest rate (percent)			6.00%