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Retirement Plan Benefits - Actual Allocation of the Assets in the Pension Plan (Details)
Dec. 31, 2014
Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]    
Actual allocation of the Pension Plan assets 100.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations 100.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
U.S. large capitalization equities    
Defined Benefit Plan Disclosure [Line Items]    
Actual allocation of the Pension Plan assets 30.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_USLargeCapitalizationEquitiesMember		 33.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_USLargeCapitalizationEquitiesMember
U.S. small capitalization equities    
Defined Benefit Plan Disclosure [Line Items]    
Actual allocation of the Pension Plan assets 6.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_USSmallCapitalizationEquitiesMember		 7.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_USSmallCapitalizationEquitiesMember
International equities    
Defined Benefit Plan Disclosure [Line Items]    
Actual allocation of the Pension Plan assets 7.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_InternationalEquitiesMember		 8.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_InternationalEquitiesMember
U.S. long-duration fixed income    
Defined Benefit Plan Disclosure [Line Items]    
Actual allocation of the Pension Plan assets 54.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_USLongDurationFixedIncomeMember		 49.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_USLongDurationFixedIncomeMember
Below Investment Grade Corporate Fixed Income    
Defined Benefit Plan Disclosure [Line Items]    
Actual allocation of the Pension Plan assets 0.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_HighYieldFixedIncomeMember		 3.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_HighYieldFixedIncomeMember
Below Investment Grade Corporate Fixed Income [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Actual allocation of the Pension Plan assets 3.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_BelowInvestmentGradeCorporateFixedIncomeMember		 0.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= emc_BelowInvestmentGradeCorporateFixedIncomeMember