Distribution Restrictions - Additional Information (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Balance of permitted transfers to parent company	$ 2,975,593	$ 2,702,633
Description of provisions on senior credit facility transfers to Lamar Advertising not subject to additional restrictions	(i) the total debt ratio is less than 6.5 to 1 and (ii) the secured debt ratio does not exceed 3.0 to 1.
Debt ratio	6.5
Debt ratio related to actual position on senior credit facility	6.5
Available cumulative credit	$ 1,726,073
Secured Debt [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Secured debt ratio	3.0
LAMAR MEDIA CORP. AND SUBSIDIARIES [Member] \| Secured Debt [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Secured debt ratio	3.0

- Definition

Amount of additional cumulative credit available for transfers to parent company under the terms of Lamar Media Corp.'s senior credit facility.

+ References

No definition available.

+ Details

Name:	lamr_AvailableCumulativeCredit
Namespace Prefix:	lamr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Balance of permitted transfers to parent company allowed under the terms of Lamar Media Corp.'s senior subordinated and senior notes.

+ References

No definition available.

+ Details

Name:	lamr_BalanceOfPermittedTransfersToParentCompany
Namespace Prefix:	lamr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Description of Provisions On senior credit facility transfers to Parent Company subject to additional restrictions.

+ References

No definition available.

+ Details

Name:	lamr_DescriptionOfProvisionsOnSeniorCreditFacilityTransfersToParentCompanySubjectToAdditionalRestrictions
Namespace Prefix:	lamr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum actual holdings debt ratio.

+ References

No definition available.

+ Details

Name:	lamr_MaximumActualHoldingsDebtRatio
Namespace Prefix:	lamr_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum holding debt ratio for applicability of restriction on transfer.

+ References

No definition available.

+ Details

Name:	lamr_MaximumHoldingDebtRatioForApplicabilityOfRestrictionOnTransfer
Namespace Prefix:	lamr_
Data Type:	xbrli:pureItemType
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

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

Name:	us-gaap_RatioOfIndebtednessToNetCapital1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
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:

- Details

Name:	us-gaap_ConsolidatedEntitiesAxis=lamr_LamarMediaCorporationAndSubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: