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Percentage of aggregate principle which may be redeemed at any time at a specified price.

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Percentage premium which may be required for repayment if the Company undergoes a change in control.

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Debt instrument redemption, percentage of debt outstanding, post redemption.

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Ratio of indebtedness to net capital minimum.

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

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

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Contractual interest rate for funds borrowed, under the debt agreement.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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

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Percentage of principal amount of debt redeemed.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Description of the frequency of the required periodic payments of interest, principal, or both, and the amount, if set, or a description of a formula upon which payment is based.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of the required periodic payments of both interest and principal.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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The cash inflow from bank borrowing during the year.

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The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

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Indebtedness divided by net capital.

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No definition available.

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Long-term Debt - Additional Information (Detail)								9 Months Ended
Long-term Debt - Additional Information (Detail)	Mar. 19, 2018	Mar. 16, 2018 USD ($)	May 15, 2017 USD ($)	Jan. 28, 2016 USD ($)	Jan. 10, 2014 USD ($)	Oct. 30, 2012 USD ($)	Feb. 09, 2012 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017
Debt Instrument [Line Items]
Proceeds received from term A loans								$ 599,250,000	$ 450,000,000
Outstanding revolving credit facility								105,000,000
Remaining borrowing capacity under revolving credit facility								332,047,000
Loss on debt extinguishment								15,429,000	71,000
5 7/8% Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Redemption price, percentage of loan	101.958%
Interest rate on convertible notes							5.875%			5.875%
Aggregate principal amount of debt issued							$ 500,000,000
Net proceeds from the issuance of debt							$ 489,000,000
Loss on debt extinguishment								15,429,000
Loss on debt extinguishment on cash								$ 9,790,000
5% Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Interest rate on convertible notes						5.00%		5.00%		5.00%
Aggregate principal amount of debt issued						$ 535,000,000
Net proceeds from the issuance of debt						$ 527,100,000
Redemption price percentage of the principal amount to be purchased						101.00%
5 3/8% Senior Notes [Member]
Debt Instrument [Line Items]
Interest rate on convertible notes					5.375%			5.375%		5.375%
Aggregate principal amount of debt issued					$ 510,000,000
Net proceeds from the issuance of debt					$ 502,300,000
Redemption price percentage of the principal amount to be purchased					101.00%
5 3/8% Senior Notes [Member] \| Prior to January 15, 2019 [Member]
Debt Instrument [Line Items]
Redemption percentage equal to principal amount include aggregate premium					100.00%
5 3/4% Senior Notes [Member]
Debt Instrument [Line Items]
Interest rate on convertible notes				5.75%				5.75%		5.75%
Aggregate principal amount of debt issued				$ 400,000,000
Net proceeds from the issuance of debt				$ 394,500,000
Redemption price percentage of the principal amount to be purchased				101.00%
5 3/4% Senior Notes [Member] \| Prior to February 1, 2019 [Member]
Debt Instrument [Line Items]
Redemption price, percentage of loan				105.75%
Redemption percentage of aggregate principal amount of senior notes				35.00%
Redemption percentage of issued notes which remain outstanding				65.00%
5 3/4% Senior Notes [Member] \| Prior to February 1, 2021 [Member]
Debt Instrument [Line Items]
Redemption price, percentage of loan				100.00%
Letter of Credit [Member]
Debt Instrument [Line Items]
Letter of credit outstanding balance								$ 12,953,000
LAMAR MEDIA CORP. AND SUBSIDIARIES [Member]
Debt Instrument [Line Items]
Proceeds received from term A loans								599,250,000	450,000,000
Loss on debt extinguishment								$ 15,429,000	$ 71,000
Term B Loan Facility [Member]
Debt Instrument [Line Items]
Amended and restated date		Mar. 16, 2018
Maximum borrowing limit of incremental loan facility		$ 600,000,000
Debt instrument maturity date		Mar. 16, 2025
Credit agreement frequency of payment and payment terms		The Term B loan began amortizing on June 30, 2018 in equal quarterly installments of $1,500 with the remainder payable at maturity
Quarterly installments, amount		$ 1,500,000
Redemption price, percentage of loan		5.875%
Senior Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing limit of incremental loan facility			$ 450,000,000
Debt instrument maturity date			May 15, 2022
Term A Loan Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing limit of incremental loan facility			$ 450,000,000
Debt instrument maturity date			May 15, 2022
Proceeds received from term A loans			$ 450,000,000
Term A Loan Facility [Member] \| LIBO Rate [Member]
Debt Instrument [Line Items]
Adjusted Rate		1.75%
Ratio of indebtedness to net capital one		3.25
Ratio of indebtedness to net capital minimum		1
Term A Loan Facility [Member] \| LIBO Rate [Member] \| Debt Ratio Less Than Three Point Two Five [Member]
Debt Instrument [Line Items]
Adjusted Rate		1.50%
Term A Loan Facility [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Adjusted Rate		0.75%
Ratio of indebtedness to net capital one		3.25
Ratio of indebtedness to net capital minimum		1
Term A Loan Facility [Member] \| Base Rate [Member] \| Debt Ratio Less Than Three Point Two Five [Member]
Debt Instrument [Line Items]
Adjusted Rate		0.50%
Term Loans [Member]
Debt Instrument [Line Items]
Debt instrument maturity date			May 15, 2022
Revolving Credit Facility [Member] \| LAMAR MEDIA CORP. AND SUBSIDIARIES [Member]
Debt Instrument [Line Items]
Debt instrument maturity date								May 15, 2022
Revolving Credit Facility [Member] \| LIBO Rate [Member]
Debt Instrument [Line Items]
Adjusted Rate		2.25%
Ratio of indebtedness to net capital one		4.25
Ratio of indebtedness to net capital minimum		1
Revolving Credit Facility [Member] \| LIBO Rate [Member] \| Debt Ratio Less Than Four Point Two Five [Member]
Debt Instrument [Line Items]
Adjusted Rate		2.00%
Revolving Credit Facility [Member] \| LIBO Rate [Member] \| Debt Ratio Less Than Three Point Zero Zero [Member]
Debt Instrument [Line Items]
Adjusted Rate		1.75%
Ratio of indebtedness to net capital one		3.00
Ratio of indebtedness to net capital minimum		1
Revolving Credit Facility [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Adjusted Rate		1.25%
Ratio of indebtedness to net capital one		4.25
Ratio of indebtedness to net capital minimum		1
Revolving Credit Facility [Member] \| Base Rate [Member] \| Debt Ratio Less Than Four Point Two Five [Member]
Debt Instrument [Line Items]
Adjusted Rate		1.00%
Revolving Credit Facility [Member] \| Base Rate [Member] \| Debt Ratio Less Than Three Point Zero Zero [Member]
Debt Instrument [Line Items]
Adjusted Rate		0.75%
Ratio of indebtedness to net capital one		3.00
Ratio of indebtedness to net capital minimum		1