Threshold period for determining trade accounts receivable as past due in 'PnYnMnDTnHnMnS' format

No definition available.

Name:	lvlt_AccountsReceivablePastDueThresholdDaysOutstanding
Namespace Prefix:	lvlt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Capitalized Labor and Related Costs Associated with Employee and Contract Labor Working on Capital Projects

+ References

No definition available.

+ Details

Name:	lvlt_CapitalizedLaborAndRelatedCostsAssociatedWithEmployeeAndContractLaborWorkingOnCapitalProjects
Namespace Prefix:	lvlt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Cumulative Effect of New Accounting Principle in Period of Adoption, Tax

+ References

No definition available.

+ Details

Name:	lvlt_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoptionTax
Namespace Prefix:	lvlt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

Name:	lvlt_NatureOfBusinessLineItems
Namespace Prefix:	lvlt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Revenue From Contract With Customer, Amortization Threshold

+ References

No definition available.

+ Details

Name:	lvlt_RevenueFromContractWithCustomerAmortizationThreshold
Namespace Prefix:	lvlt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Revenue from Contract with Customer, Contract Term

+ References

No definition available.

+ Details

Name:	lvlt_RevenueFromContractWithCustomerContractTerm
Namespace Prefix:	lvlt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Revenue from Contract with Customer, Length of Customer Life

+ References

No definition available.

+ Details

Name:	lvlt_RevenueFromContractWithCustomerLengthOfCustomerLife
Namespace Prefix:	lvlt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the customer relationship period considered for recognition of revenue.

+ References

No definition available.

+ Details

Name:	lvlt_RevenueRecognitionCustomerRelationshipPeriod
Namespace Prefix:	lvlt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect

+ References

No definition available.

+ Details

Name:	lvlt_TaxCutsandJobsActReclassificationfromAOCItoRetainedEarningsTaxEffect
Namespace Prefix:	lvlt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Universal Service Fund Contributions

+ References

No definition available.

+ Details

Name:	lvlt_UniversalServiceFundContributions
Namespace Prefix:	lvlt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

+ References

No definition available.

+ Details

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

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13854-109267

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13777-109266

+ Details

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

- Definition

Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfReportingUnits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_RetainedEarningsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201409Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_ComputerSoftwareIntangibleAssetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_OtherIntangibleAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_PredecessorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Background and Summary of Significant Accounting Policies (Details)	2 Months Ended	3 Months Ended	10 Months Ended	12 Months Ended
	Dec. 31, 2017 USD ($)	Mar. 31, 2018 USD ($)	Oct. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) reporting_unit	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Description of Business
Amortization threshold				$ 50,000
USF contributions	$ 71,000,000			$ 415,000,000
Past due threshold, days outstanding				30 days
Capitalized labor and related costs associated with employee and contract labor working on capital projects	$ 32,000,000			$ 95,000,000
Finite-lived intangible assets, useful life				11 years
Goodwill impairment				$ 0	$ 0
Number of reporting units \| reporting_unit				1
Reclassification from AOCI to retained earnings, tax effect		$ 6,000,000
Accumulated deficit \| Accounting Standards Update 2014-09
Description of Business
Cumulative effect of adoption of ASU				$ 9,000,000
Cumulative net effect of adoption of ASU, tax				$ 3,000,000
Customer relationships
Description of Business
Finite-lived intangible assets, useful life				11 years
Capitalized software
Description of Business
Finite-lived intangible assets, useful life				7 years
Other
Description of Business
Finite-lived intangible assets, useful life				5 years
Minimum
Description of Business
Contract term				1 year
Period company may receive up front payments for services to be provided in the future (in years)				10 years
Minimum \| Customer relationships
Description of Business
Finite-lived intangible assets, useful life				7 years
Maximum
Description of Business
Contract term				7 years
Period company may receive up front payments for services to be provided in the future (in years)				20 years
Maximum \| Customer relationships
Description of Business
Finite-lived intangible assets, useful life				14 years
Weighted Average
Description of Business
Length of customer life				30 months
Predecessor
Description of Business
USF contributions			$ 331,000,000			$ 414,000,000
Capitalized labor and related costs associated with employee and contract labor working on capital projects			$ 178,000,000			$ 210,000,000