Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ 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)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 9

+ Details

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

- Definition

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

+ References

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=34725769&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=6451184&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
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

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
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

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

+ Details

Name:	us-gaap_DebtInstrumentRedemptionPricePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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

Amount of interest capitalized during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Allowance for Funds Used during Construction
-URI http://asc.fasb.org/extlink&oid=6504829

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

+ Details

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

- Definition

Total interest costs incurred during the period and either capitalized or charged against earnings.

+ References

+ Details

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

- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.9)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of interest expense incurred on a debt or other obligation to related party.

+ References

No definition available.

+ Details

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

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

- Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=ctq_Notes6.625due2055Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ctq_Notes6.875percentdue2054Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ctq_Notes7.500percentdue2014Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ctq_Notes7.200due2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ctq_Notes6.875Due2033Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ctq_Notes7.625PercentDue2015Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ctq_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=ctq_A7.00Notesdue2056Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
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:

Long-Term Debt and Revolving Promissory Note Long-Term Debt and Revolving Promissory Note (Details 2) - USD ($) $ in Millions					12 Months Ended
	Jan. 31, 2016	Sep. 21, 2015	Feb. 20, 2015	Sep. 29, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Oct. 13, 2015	Sep. 30, 2015	Jun. 15, 2015	Oct. 01, 2014
Debt Instrument [Line Items]
Long-term debt, gross					$ 7,346
Amount of gross interest expense, net of capitalized interest and interest expense - affiliates
Gross interest expense					491	$ 481	$ 467
Capitalized interest					(18)	(17)	(17)
Total interest expense					473	464	450
Interest expense-affiliates, net					53	40	$ 64
Senior notes
Debt Instrument [Line Items]
Long-term debt, gross					7,229	7,311
Term loan
Debt Instrument [Line Items]
Long-term debt, gross					$ 100	$ 0
Qwest Corporation \| Senior notes \| 6.625% Notes due 2055
Debt Instrument [Line Items]
Face amount of debt instrument		$ 400							$ 10
Interest rate, stated percentage (as a percent)		6.625%
Net proceeds from issuance of debt		$ 386
Qwest Corporation \| Senior notes \| 6.625% Notes due 2055 \| Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price of debt instrument (as a percent)		100.00%
Qwest Corporation \| Senior notes \| 6.875 % Notes due 2054
Debt Instrument [Line Items]
Face amount of debt instrument				$ 500
Interest rate, stated percentage (as a percent)				6.875%
Net proceeds from issuance of debt				$ 483
Qwest Corporation \| Senior notes \| 6.875 % Notes due 2054 \| Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price of debt instrument (as a percent)				100.00%
Qwest Corporation \| Senior notes \| 7.50%Notes due 2014
Debt Instrument [Line Items]
Interest rate, stated percentage (as a percent)											7.50%
Repurchased face amount of Senior notes											$ 600
Qwest Corporation \| Senior notes \| 7.200% Notes due 2026
Debt Instrument [Line Items]
Interest rate, stated percentage (as a percent)								7.20%
Repurchased face amount of Senior notes								$ 250
Qwest Corporation \| Senior notes \| 6.875% Noted due 2033
Debt Instrument [Line Items]
Interest rate, stated percentage (as a percent)								6.875%
Repurchased face amount of Senior notes								$ 150
Qwest Corporation \| Senior notes \| 7.625% Noted due 2015
Debt Instrument [Line Items]
Interest rate, stated percentage (as a percent)										7.625%
Repurchased face amount of Senior notes										$ 92
Qwest Corporation \| Term loan \| Term loan
Debt Instrument [Line Items]
Long-term debt, gross			$ 100
Face amount of debt instrument			$ 100
Subsequent event \| Qwest Corporation \| Senior notes \| 7.00% Notes due 2056
Debt Instrument [Line Items]
Face amount of debt instrument	$ 235
Interest rate, stated percentage (as a percent)	7.00%
Net proceeds from issuance of debt	$ 227
Subsequent event \| Qwest Corporation \| Senior notes \| 7.00% Notes due 2056 \| Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price of debt instrument (as a percent)	100.00%
Minimum \| Senior notes
Debt Instrument [Line Items]
Interest rate, stated percentage (as a percent)					6.125%
Minimum \| London Interbank Offered Rate (LIBOR) \| Qwest Corporation \| Term loan \| Term loan
Debt Instrument [Line Items]
Interest rate margin (as a percent)			1.50%
Minimum \| Base Rate \| Qwest Corporation \| Term loan \| Term loan
Debt Instrument [Line Items]
Interest rate margin (as a percent)			0.50%
Maximum \| Senior notes
Debt Instrument [Line Items]
Interest rate, stated percentage (as a percent)					8.375%
Maximum \| London Interbank Offered Rate (LIBOR) \| Qwest Corporation \| Term loan \| Term loan
Debt Instrument [Line Items]
Interest rate margin (as a percent)			2.50%
Maximum \| Base Rate \| Qwest Corporation \| Term loan \| Term loan
Debt Instrument [Line Items]
Interest rate margin (as a percent)			1.50%