| Investments In Available-For-Sale Securities And Other Cost Investments (Details) (USD $)In Millions, unless otherwise specified
 | 1 Months Ended | 12 Months Ended |  | 
      
        | Apr. 30, 2014 | Dec. 31, 2014 | Dec. 31, 2013 | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | $ 816us-gaap_AvailableForSaleSecuritiesNoncurrent | $ 1,324us-gaap_AvailableForSaleSecuritiesNoncurrent | 
      
        | Other Investments [Member] | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | 47us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
 = us-gaap_OtherInvestmentsMember
 | 47us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
 = us-gaap_OtherInvestmentsMember
 | 
      
        | AFS and cost method investments | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | 71us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
 = lmca_AfsAndCostMethodInvestmentsMember
 | 71us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
 = lmca_AfsAndCostMethodInvestmentsMember
 | 
      
        | Barnes & Noble, Inc. | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Sale of stock, ownership percentage of cost investment after transaction | Ìý | 2.00%lmca_Saleofstockownershippercentageofcostinvestmentaftertransaction / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_BarnesNobleIncMember
 | Ìý | 
      
        | Percentage of shares sold | 90.00%lmca_Percentageofsharessold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_BarnesNobleIncMember
 | Ìý | Ìý | 
      
        | Proceeds from Sale of Available-for-sale Securities | Ìý | 247us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_BarnesNobleIncMember
 | Ìý | 
      
        | Live Nation | Debt Securities | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | 24us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
 = us-gaap_DebtSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_LiveNationMember
 | 24us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
 = us-gaap_DebtSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_LiveNationMember
 | 
      
        | Fair Value Option Securities | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | 745us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 | 1,253us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 | 
      
        | Fair Value Option Securities | Time Warner Inc | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | 363us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_TimeWarnerIncMember
 | 297us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_TimeWarnerIncMember
 | 
      
        | Fair Value Option Securities | Time Warner Cable Inc | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | Ìý | 320us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_TimeWarnerCableIncMember
 | 
      
        | Fair Value Option Securities | Viacom, Inc. | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | 273us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_ViacomIncMember
 | 317us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_ViacomIncMember
 | 
      
        | Fair Value Option Securities | Barnes & Noble, Inc. | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | 27us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_BarnesNobleIncMember
 | 255us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_BarnesNobleIncMember
 | 
      
        | Fair Value Option Securities | Other AFS Equity Securities | Equity Securities | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | 55us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
 = us-gaap_EquitySecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_OtherAfsEquitySecuritiesMember
 | 37us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
 = us-gaap_EquitySecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_OtherAfsEquitySecuritiesMember
 | 
      
        | Fair Value Option Securities | Other AFS Debt Securities | Debt Securities | Ìý | Ìý | Ìý | 
      
        | Schedule of Investments [Line Items] | Ìý | Ìý | Ìý | 
      
        | Investments in available-for-sale securities and other cost investments | Ìý | $ 27us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
 = us-gaap_DebtSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_OtherAfsDebtSecuritiesMember
 | $ 27us-gaap_AvailableForSaleSecuritiesNoncurrent / us-gaap_EligibleItemOrGroupForFairValueOptionAxis
 = lmca_FairValueOptionSecuritiesMember
 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
 = us-gaap_DebtSecuritiesMember
 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
 = lmca_OtherAfsDebtSecuritiesMember
 |