Debt instrument redemption amount.

No definition available.

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

- Definition

Debt instrument redemption date.

+ References

No definition available.

+ Details

Name:	lamr_DebtInstrumentRedemptionDate
Namespace Prefix:	lamr_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ 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

Reference 1: 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(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

The cash inflow from bank borrowing during the year.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=lamr_ThreePointFiveByEightPercentSeniorNotesMember
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_LongtermDebtTypeAxis=lamr_FivePointThreeByFourPercentSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Subsequent Events - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Jan. 22, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2018	Mar. 31, 2021	Feb. 03, 2021	Feb. 06, 2020	Dec. 31, 2019	Jan. 28, 2016
Subsequent Event [Line Items]
Aggregate principal amount of debt issued			$ 2,926,633		$ 2,880,369
Debt Instrument, Interest Rate, Stated Percentage						5.75%	4.00%
Proceeds received from term loans		$ 598,500	$ 598,500	$ 599,250
3 5/8% Senior Notes [Member]
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					3.58%
3 5/8% Senior Notes [Member] \| Subsequent Events [Member]
Subsequent Event [Line Items]
Aggregate principal amount of debt issued	$ 550,000
Debt Instrument, Interest Rate, Stated Percentage	3.625%
Proceeds received from term loans	$ 542,500
5 3/4% Senior Notes [Member]
Subsequent Event [Line Items]
Aggregate principal amount of debt issued									$ 400,000
Debt Instrument, Interest Rate, Stated Percentage			5.75%					5.75%	5.75%
5 3/4% Senior Notes [Member] \| Subsequent Events [Member]
Subsequent Event [Line Items]
Debt instrument redemption amount	$ 650,000
Debt Instrument, Interest Rate, Stated Percentage	5.75%
Debt instrument redemption date	Feb. 03, 2021