Annual report pursuant to Section 13 and 15(d)

Investments In Available-For-Sale Securities And Other Cost Investments (Details)

v2.4.1.9
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]      
Investments in available-for-sale securities and other cost investments   $ 816us-gaap_AvailableForSaleSecuritiesNoncurrent $ 1,324us-gaap_AvailableForSaleSecuritiesNoncurrent
Other Investments [Member]      
Schedule of Investments [Line Items]      
Investments in available-for-sale securities and other cost investments   47us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherInvestmentsMember
47us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherInvestmentsMember
AFS and cost method investments      
Schedule of Investments [Line Items]      
Investments in available-for-sale securities and other cost investments   71us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= lmca_AfsAndCostMethodInvestmentsMember
71us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= lmca_AfsAndCostMethodInvestmentsMember
Barnes & Noble, Inc.      
Schedule of Investments [Line Items]      
Sale of stock, ownership percentage of cost investment after transaction   2.00%lmca_Saleofstockownershippercentageofcostinvestmentaftertransaction
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= lmca_BarnesNobleIncMember
 
Percentage of shares sold 90.00%lmca_Percentageofsharessold
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= lmca_BarnesNobleIncMember
   
Proceeds from Sale of Available-for-sale Securities   247us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= lmca_BarnesNobleIncMember
 
Live Nation | Debt Securities      
Schedule of Investments [Line Items]      
Investments in available-for-sale securities and other cost investments   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      
Schedule of Investments [Line Items]      
Investments in available-for-sale securities and other cost investments   745us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= lmca_FairValueOptionSecuritiesMember
1,253us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= lmca_FairValueOptionSecuritiesMember
Fair Value Option Securities | Time Warner Inc      
Schedule of Investments [Line Items]      
Investments in available-for-sale securities and other cost investments   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      
Schedule of Investments [Line Items]      
Investments in available-for-sale securities and other cost investments     320us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= lmca_FairValueOptionSecuritiesMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= lmca_TimeWarnerCableIncMember
Fair Value Option Securities | Viacom, Inc.      
Schedule of Investments [Line Items]      
Investments in available-for-sale securities and other cost investments   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.      
Schedule of Investments [Line Items]      
Investments in available-for-sale securities and other cost investments   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      
Schedule of Investments [Line Items]      
Investments in available-for-sale securities and other cost investments   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      
Schedule of Investments [Line Items]      
Investments in available-for-sale securities and other cost investments   $ 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