Fair Value of Financial Assets and Liabilities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014 Security	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Number of Auction Rate Securities With Underlying Loans Which Have No Guarantees	1
Gain on sale of investment	$ 101us-gaap_GainOnSaleOfInvestments
Auction rate securities that have partial guarantees by the U.S. government, market value	7emc_AuctionRateSecuritiesAtFairValue
Percentage of loans which collateralize auction rate securities guaranteed by FFELP	95.00%emc_PercentageOfLoansGuaranteed
Discount rate used to estimate fair value of investments	1.00%us-gaap_FairValueInputsDiscountRate
Investment holding period	5 years
The rate used for the discount margin to determine the estimated fair value of investment in auction rate securities	1.00%	1.00%
Short term investment, not classified in investments due within one year	1,978us-gaap_ShortTermInvestments	2,773us-gaap_ShortTermInvestments
Minimum
Schedule of Available-for-sale Securities [Line Items]
Coupon rate used to estimate fair value of invesments - low end of range	0.00%
Maximum
Schedule of Available-for-sale Securities [Line Items]
Coupon rate used to estimate fair value of invesments - high end of range	3.00%
Municipal obligations
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	950	863
Publicly traded equity securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	209	95
High yield corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	563	531
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	53
Securities (Assets)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	8,312	9,697
Foreign debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	2,564	2,155
Average credit rating	A+
Foreign Sovereign Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Average credit rating	AA+
Percentage of securities deemed soverign debt	5.00%
Auction rate securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	27	60
Average credit rating	AA
Variable Rate Demand Note
Schedule of Available-for-sale Securities [Line Items]
Short term investment, not classified in investments due within one year	32
Contractual maturity date	Dec. 31, 2015
XtremIO
Schedule of Available-for-sale Securities [Line Items]
Gain on sale of investment		$ 32
LenovoEMC
Schedule of Available-for-sale Securities [Line Items]
Joint Venture, Ownership Interest Percentage	49.00%
Discount rate used to estimate fair value of investments	6.00%

Auction rate securities, at Fair Value

No definition available.

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- Definition

Description of the average credit rating indicative of likelihood of repayment of debt instruments given by credit rating agencies (for example, Standard and Poor's, Moody's, Fitch).

+ References

No definition available.

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- Definition

Financial Instruments Fair Value Assumptions Weighted Average Discount Rate

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- Definition

Investment Holding Period

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No definition available.

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- Definition

The highest interest rate in the aggregated short-tem debt instruments.

+ References

No definition available.

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- Definition

The lowest interest rate in the aggregated short-tem debt instruments.

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Joint Venture, Ownership Interest Percentage

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No definition available.

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- Definition

Number of Auction Rate Securities With Underlying Loans Which Have No Guarantees

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No definition available.

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- Definition

-- None. No documentation exists for this element. --

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No definition available.

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- Definition

Percentage of Loans Guaranteed

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No definition available.

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

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- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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- Definition

The difference between the carrying value and the sale price of an investment. A gain would be recognized when the sale price of the investment is greater than the carrying value of the investment. This element refers to the Gain included in earnings and not to the cash proceeds of the sale.

+ References

No definition available.

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- Definition

Investments which are intended to be sold in the short term (usually less than one year or the normal operating cycle, whichever is longer) including trading securities, available-for-sale securities, held-to-maturity securities, and other short-term investments not otherwise listed in the existing taxonomy.

+ References

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-Name Accounting Standards Codification

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