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Non-cash Financing and Investing Activities - Additional Information (Detail) (USD $)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Supplemental Disclosure Of Non Cash Investing And Financing Information [Line Items]    
Non-cash acquisition of capital expenditures and outdoor advertising assets $ 1,900,000lamr_NonCashAcquisitionOfOutdoorAdvertisingAssets $ 4,982,000lamr_NonCashAcquisitionOfOutdoorAdvertisingAssets
Treasury stock retired shares 17,270,930us-gaap_TreasuryStockSharesRetired  
Treasury stock retired value 896,818,000us-gaap_TreasuryStockRetiredParValueMethodAmount  
Non-cash financing activity   0lamr_NonCashFinancingTransaction
LAMAR MEDIA CORP [Member]    
Supplemental Disclosure Of Non Cash Investing And Financing Information [Line Items]    
Non-cash acquisition of capital expenditures and outdoor advertising assets 1,900,000lamr_NonCashAcquisitionOfOutdoorAdvertisingAssets
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember		 4,982,000lamr_NonCashAcquisitionOfOutdoorAdvertisingAssets
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Non-cash financing activity $ 0lamr_NonCashFinancingTransaction
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember		 $ 0lamr_NonCashFinancingTransaction
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember