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Shareholders' Equity - Additional Information (Detail) (USD $)
Dec. 31, 2014
Dec. 31, 2013
Feb. 23, 2015
Class of Stock [Line Items]      
Common stock, shares authorized 100,000,000us-gaap_CommonStockSharesAuthorized 100,000,000us-gaap_CommonStockSharesAuthorized  
Common stock, par value $ 0.01us-gaap_CommonStockParOrStatedValuePerShare $ 0.01us-gaap_CommonStockParOrStatedValuePerShare  
Common stock reserved for issuance under stock-based plans 3,934,000us-gaap_CommonStockCapitalSharesReservedForFutureIssuance    
Common stock remaining under repurchase authorization 5,041,900us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased    
Preferred stock, shares authorized 10,000,000us-gaap_PreferredStockSharesAuthorized 10,000,000us-gaap_PreferredStockSharesAuthorized  
Preferred stock, par value $ 0.01us-gaap_PreferredStockParOrStatedValuePerShare $ 0.01us-gaap_PreferredStockParOrStatedValuePerShare  
Percentage ownership by person or group making rights exercisable 15.00%mlm_PercentageOwnershipByPersonOrGroupMakingRightsExercisable    
Rights exercisable price, per share $ 315us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1    
Rights redemption price, per right $ 0.001us-gaap_PreferredStockRedemptionPricePerShare    
Class B Preferred Stock      
Class of Stock [Line Items]      
Preferred stock reserved for issuance under stock-based plans 200,000us-gaap_PreferredStockCapitalSharesReservedForFutureIssuance
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassBMember
   
Subsequent Event      
Class of Stock [Line Items]      
Stock repurchase program, shares authorized to be repurchased     20,000,000us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember