| Condensed Consolidated Statements Of Equity (USD $)In Millions, unless otherwise specified
 | Common Stock
 Common Class A | Common Stock
 Common Class C | Additional Paid-in Capital
 Starz, LLC | Additional Paid-in Capital
 Liberty Broadband | Additional Paid-in Capital | Accumulated Other Comprehensive Income (Loss)
 Starz, LLC | Accumulated Other Comprehensive Income (Loss)
 Liberty Broadband | Accumulated Other Comprehensive Income (Loss) | Retained Earnings
 Liberty Broadband | Retained Earnings | Noncontrolling Interest
 Starz, LLC | Noncontrolling Interest | Starz, LLC | Liberty Broadband | Total | 
      
        | Balance at Dec. 31, 2011 | $ 1us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementClassOfStockAxis
 = us-gaap_CommonClassAMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_CommonStockMember
 | $ 2us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementClassOfStockAxis
 = us-gaap_CommonClassCMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_CommonStockMember
 |  |  | $ 3,562us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  | $ 29us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AccumulatedOtherComprehensiveIncomeMember
 |  | $ 1,665us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_RetainedEarningsMember
 |  | $ (10)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | $ 5,249us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 
      
        | Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 
      
        | Net Income (Loss), Including Portion Attributable to Noncontrolling Interest |  |  |  |  |  |  |  |  |  | 1,414us-gaap_ProfitLoss / us-gaap_StatementEquityComponentsAxis
 = us-gaap_RetainedEarningsMember
 |  | (2)us-gaap_ProfitLoss / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | 1,412us-gaap_ProfitLoss | 
      
        | Other Comprehensive Income (Loss), Net of Tax |  |  |  |  |  |  |  | (17)us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AccumulatedOtherComprehensiveIncomeMember
 |  |  |  |  |  |  | (17)us-gaap_OtherComprehensiveIncomeLossNetOfTax | 
      
        | Stock compensation |  |  |  |  | 68us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | 68us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue | 
      
        | Minimum withholding taxes on net share settlements of stock-based compensation |  |  |  |  | (181)us-gaap_AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | (181)us-gaap_AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet | 
      
        | Excess tax benefits on stock-based compensation |  |  |  |  | 146us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | 146us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation | 
      
        | Stock issued upon exercise of stock options |  |  |  |  | 7us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | 7us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised | 
      
        | Series A Liberty stock repurchase |  |  |  |  | (323)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | (323)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue | 
      
        | Non-cash benefit from reversal of contingent liability |  |  |  |  | 72lmca_AdjustmentsToAdditionalPaidInCapitalTaxBenefitFromTransactionsWithFormerParent / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | 72lmca_AdjustmentsToAdditionalPaidInCapitalTaxBenefitFromTransactionsWithFormerParent | 
      
        | Other |  |  |  |  | (5)us-gaap_StockholdersEquityOther / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  | 4us-gaap_StockholdersEquityOther / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | (1)us-gaap_StockholdersEquityOther | 
      
        | Balance at Dec. 31, 2012 | 1us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementClassOfStockAxis
 = us-gaap_CommonClassAMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_CommonStockMember
 | 2us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementClassOfStockAxis
 = us-gaap_CommonClassCMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_CommonStockMember
 |  |  | 3,346us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  | 12us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AccumulatedOtherComprehensiveIncomeMember
 |  | 3,079us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_RetainedEarningsMember
 |  | (8)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | 6,432us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 
      
        | Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 
      
        | Net Income (Loss), Including Portion Attributable to Noncontrolling Interest |  |  |  |  |  |  |  |  |  | 8,780us-gaap_ProfitLoss / us-gaap_StatementEquityComponentsAxis
 = us-gaap_RetainedEarningsMember
 |  | 211us-gaap_ProfitLoss / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | 8,991us-gaap_ProfitLoss | 
      
        | Other Comprehensive Income (Loss), Net of Tax |  |  |  |  |  |  |  | (11)us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AccumulatedOtherComprehensiveIncomeMember
 |  |  |  |  |  |  | (11)us-gaap_OtherComprehensiveIncomeLossNetOfTax | 
      
        | Stock compensation |  |  |  |  | 140us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  | 63us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | 203us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue | 
      
        | Minimum withholding taxes on net share settlements of stock-based compensation |  |  |  |  | (51)us-gaap_AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | (51)us-gaap_AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet | 
      
        | Series A Liberty stock repurchase |  |  |  |  | (140)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | (140)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue | 
      
        | Shares repurchased by subsidiary |  |  |  |  | (160)us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesRepurchaseOfSharesBySubsidiary / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  | (1,442)us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesRepurchaseOfSharesBySubsidiary / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | (1,602)us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesRepurchaseOfSharesBySubsidiary | 
      
        | Shares issued by subsidiary |  |  |  |  | (61)us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesIssuanceOfEquityBySubsidiaryToNoncontrollingInterests / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  | 127us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesIssuanceOfEquityBySubsidiaryToNoncontrollingInterests / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | 66us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesIssuanceOfEquityBySubsidiaryToNoncontrollingInterests | 
      
        | Shares acquired in disposition of subsidiary |  |  |  |  | (937)lmca_StockRepurchaseAndRetiredDuringPeriodValueInDispositionOfSubsidiary / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | (937)lmca_StockRepurchaseAndRetiredDuringPeriodValueInDispositionOfSubsidiary | 
      
        | Issuance of Warrants |  |  |  |  | 170us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | 170us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued | 
      
        | Non-controlling interest recognized with acquisition of a controlling interest in a subsidiary |  |  |  |  |  |  |  |  |  |  |  | 10,841us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | 10,841us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination | 
      
        | Distribution to stockholders for spin-off |  |  | (92)lmca_EquityImpactFromProRataDistributionToShareholdersOfSubsidiary / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
 = lmca_StarzLlcMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  | 3lmca_EquityImpactFromProRataDistributionToShareholdersOfSubsidiary / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
 = lmca_StarzLlcMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AccumulatedOtherComprehensiveIncomeMember
 |  |  |  |  | 9lmca_EquityImpactFromProRataDistributionToShareholdersOfSubsidiary / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
 = lmca_StarzLlcMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  | (80)lmca_EquityImpactFromProRataDistributionToShareholdersOfSubsidiary / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
 = lmca_StarzLlcMember
 |  |  | 
      
        | Noncontrolling interests in equity of subsidiaries |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9,801us-gaap_MinorityInterest | 
      
        | Balance at Dec. 31, 2013 | 1us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementClassOfStockAxis
 = us-gaap_CommonClassAMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_CommonStockMember
 | 2us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementClassOfStockAxis
 = us-gaap_CommonClassCMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_CommonStockMember
 |  |  | 2,215us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  | 4us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AccumulatedOtherComprehensiveIncomeMember
 |  | 11,859us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_RetainedEarningsMember
 |  | 9,801us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | 23,882us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 
      
        | Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 
      
        | Net Income (Loss), Including Portion Attributable to Noncontrolling Interest |  |  |  |  |  |  |  |  |  | 178us-gaap_ProfitLoss / us-gaap_StatementEquityComponentsAxis
 = us-gaap_RetainedEarningsMember
 |  | 217us-gaap_ProfitLoss / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | 395us-gaap_ProfitLoss | 
      
        | Other Comprehensive Income (Loss), Net of Tax |  |  |  |  |  |  |  | (17)us-gaap_OtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AccumulatedOtherComprehensiveIncomeMember
 |  |  |  |  |  |  | (17)us-gaap_OtherComprehensiveIncomeLossNetOfTax | 
      
        | Stock compensation |  |  |  |  | 135us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  | 67us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | 202us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue | 
      
        | Minimum withholding taxes on net share settlements of stock-based compensation |  |  |  |  | (48)us-gaap_AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | (48)us-gaap_AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet | 
      
        | Shares repurchased by subsidiary |  |  |  |  | (179)us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesRepurchaseOfSharesBySubsidiary / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  | (2,004)us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesRepurchaseOfSharesBySubsidiary / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | (2,183)us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesRepurchaseOfSharesBySubsidiary | 
      
        | Shares issued by subsidiary |  |  |  |  | (27)us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesIssuanceOfEquityBySubsidiaryToNoncontrollingInterests / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  | 27us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesIssuanceOfEquityBySubsidiaryToNoncontrollingInterests / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  |  | 
      
        | Shares issued by subsidiary on conversion of bonds |  |  |  |  | (179)lmca_AdjustmentsToAdditionalPaidInCapitalStockIssuedBySubsidiaryOnConversionOfBonds / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  | 670lmca_AdjustmentsToAdditionalPaidInCapitalStockIssuedBySubsidiaryOnConversionOfBonds / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | 491lmca_AdjustmentsToAdditionalPaidInCapitalStockIssuedBySubsidiaryOnConversionOfBonds | 
      
        | Distribution to stockholders for spin-off |  |  |  | (1,912)lmca_EquityImpactFromProRataDistributionToShareholdersOfSubsidiary / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
 = lmca_LibertyBroadbandMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  | (8)lmca_EquityImpactFromProRataDistributionToShareholdersOfSubsidiary / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
 = lmca_LibertyBroadbandMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AccumulatedOtherComprehensiveIncomeMember
 |  | (621)lmca_EquityImpactFromProRataDistributionToShareholdersOfSubsidiary / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
 = lmca_LibertyBroadbandMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_RetainedEarningsMember
 |  |  |  |  | (2,541)lmca_EquityImpactFromProRataDistributionToShareholdersOfSubsidiary / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
 = lmca_LibertyBroadbandMember
 |  | 
      
        | Other |  |  |  |  | (5)us-gaap_StockholdersEquityOther / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AdditionalPaidInCapitalMember
 |  |  |  |  |  |  |  |  |  | (5)us-gaap_StockholdersEquityOther | 
      
        | Noncontrolling interests in equity of subsidiaries |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8,778us-gaap_MinorityInterest | 
      
        | Balance at Dec. 31, 2014 | $ 1us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementClassOfStockAxis
 = us-gaap_CommonClassAMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_CommonStockMember
 | $ 2us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementClassOfStockAxis
 = us-gaap_CommonClassCMember
 / us-gaap_StatementEquityComponentsAxis
 = us-gaap_CommonStockMember
 |  |  |  |  |  | $ (21)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_AccumulatedOtherComprehensiveIncomeMember
 |  | $ 11,416us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_RetainedEarningsMember
 |  | $ 8,778us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis
 = us-gaap_NoncontrollingInterestMember
 |  |  | $ 20,176us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest |