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Acquisitions - Weighted-Average Assumptions Used to Calculate Fair Value of Stock Options Issued (Details)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2012
Dec. 31, 2013
All 2014 Acquisitions, excluding Airwatch      
Business Acquisition [Line Items]      
Expected term (in years) 2 years 6 months 20 days    
Expected volatility 27.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_BusinessAcquisitionAxis
= emc_All2014AcquisitionsexcludingAirwatchMember
   
Risk-free interest rate 0.70%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_BusinessAcquisitionAxis
= emc_All2014AcquisitionsexcludingAirwatchMember
   
Dividend yield 1.70%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_BusinessAcquisitionAxis
= emc_All2014AcquisitionsexcludingAirwatchMember
   
2012 Acquisitions, excluding Nicira      
Business Acquisition [Line Items]      
Expected term (in years)   1 year 9 months 44 days  
Expected volatility   31.60%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_BusinessAcquisitionAxis
= emc_Acquisitions2012OtherMember
 
Risk-free interest rate   0.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_BusinessAcquisitionAxis
= emc_Acquisitions2012OtherMember
 
All 2013 Acquisitions      
Business Acquisition [Line Items]      
Expected term (in years)     1 year 8 months 44 days
Expected volatility     26.40%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_BusinessAcquisitionAxis
= emc_All2013AcquisitionsMember
Risk-free interest rate     0.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_BusinessAcquisitionAxis
= emc_All2013AcquisitionsMember
Dividend yield     1.50%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_BusinessAcquisitionAxis
= emc_All2013AcquisitionsMember
VMware | Nicira      
Business Acquisition [Line Items]      
Fair Value Assumptions, Expected Term   2 years 7 months 30 days  
Expected volatility   35.70%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_BusinessAcquisitionAxis
= emc_NiciraMember
/ dei_LegalEntityAxis
= emc_VmwareMember
 
Risk-free interest rate   0.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_BusinessAcquisitionAxis
= emc_NiciraMember
/ dei_LegalEntityAxis
= emc_VmwareMember