Long-Term Debt - Debt Maturities (Details) $ in Millions	Sep. 30, 2021 USD ($)
Debt Disclosure [Abstract]
2021 (remaining three months)	$ 7
2022	24
2023	27
2024	32
2025	837
2026 and thereafter	9,522
Total long-term debt	$ 10,449

Long-Term Debt And Financing Lease Obligations, Maturities, Repayments of Principal In Year Four

No definition available.

Name:	lumn_LongTermDebtAndFinancingLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearFour
Namespace Prefix:	lumn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Long-Term Debt And Financing Lease Obligations, Maturities, Repayments Of Principal in Year One

+ References

No definition available.

+ Details

Name:	lumn_LongTermDebtAndFinancingLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearOne
Namespace Prefix:	lumn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Long-Term Debt And Financing Lease Obligations, Maturities, Repayments Of Principal In Year Two

+ References

No definition available.

+ Details

Name:	lumn_LongTermDebtAndFinancingLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearTwo
Namespace Prefix:	lumn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Long-Term Debt And Financing Lease Obligations, Maturities, Repayments Of Principal Remainder Of Fiscal Year

+ References

No definition available.

+ Details

Name:	lumn_LongTermDebtAndFinancingLeaseObligationsMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear
Namespace Prefix:	lumn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Long-Term Debt And Financing Lease Obligations, Maturities, Repayments Of Principal, Year Five And Thereafter

+ References

No definition available.

+ Details

Name:	lumn_LongTermDebtAndFinancingLeaseObligationsMaturitiesRepaymentsOfPrincipalYearFiveAndThereafter
Namespace Prefix:	lumn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Long-term Debt and Financing Lease Obligations, Maturities, Repayments of Principal in Year Three

+ References

No definition available.

+ Details

Name:	lumn_LongtermDebtandFinancingLeaseObligationsMaturitiesRepaymentsofPrincipalinYearThree
Namespace Prefix:	lumn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-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=120391452&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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