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Benefit Plans - Additional Information (Detail) (USD $)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]      
Letters of credit with bank $ 6,624,000us-gaap_LettersOfCreditOutstandingAmount    
Employees eligibility Completed one year of service and are at least 21 years of age    
Minimum years of service required to participate in Company sponsored saving and profit sharing plan 1 year    
Minimum age required to participate in Company sponsored saving and profit sharing plan 21lamr_MinimumAgeRequiredToParticipateInCompanySponsoredSavingsAndProfitSharingPlan    
Employers contribution and compensation Match 50% of employees' contributions up to 5% of eligible compensation    
Employers contribution as percentage of employees contribution 50.00%lamr_EmployersContributionAsPercentageOfEmployeesContribution    
Employers contribution as percentage of employees compensation 5.00%lamr_EmployersContributionAsPercentageOfEmployeesCompensation    
Employees contribution limit 100.00%lamr_PercentageOfEmployeesContributionLimit    
Fully vesting period of contribution 3 years    
Minimum age for entitlement to benefit of deferred compensation plan 30lamr_MinimumAgeForEntitlementToBenefitOfDeferredCompensationPlan    
Minimum years of experience to attain the benefit of deferred compensation plan 10 years    
Deferred compensation arrangement with individual employees contribution minimum 3,000lamr_DeferredCompensationArrangementWithIndividualEmployeesContributionMinimum    
Deferred compensation arrangement with individual employees contribution maximum 8,000lamr_DeferredCompensationArrangementWithIndividualEmployeesContributionMaximum    
Deferred Profit Sharing [Member]      
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]      
Employer's contribution 3,973,000us-gaap_DeferredCompensationArrangementWithIndividualEmployerContribution
/ us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_DeferredProfitSharingMember		 3,581,000us-gaap_DeferredCompensationArrangementWithIndividualEmployerContribution
/ us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_DeferredProfitSharingMember		 3,184,000us-gaap_DeferredCompensationArrangementWithIndividualEmployerContribution
/ us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_DeferredProfitSharingMember
Deferred Compensation Plan [Member]      
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]      
Employer's contribution $ 1,400,000us-gaap_DeferredCompensationArrangementWithIndividualEmployerContribution
/ us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis
= lamr_DeferredCompensationPlanMember		 $ 1,323,000us-gaap_DeferredCompensationArrangementWithIndividualEmployerContribution
/ us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis
= lamr_DeferredCompensationPlanMember		 $ 1,260,000us-gaap_DeferredCompensationArrangementWithIndividualEmployerContribution
/ us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis
= lamr_DeferredCompensationPlanMember