Shareholders' Equity - Reconciliation from Basic To Diluted Earnings Per Share for both Numerators and Denominators (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Numerator:
Net income attributable to EMC Corporation	$ 252us-gaap_NetIncomeLoss	$ 392us-gaap_NetIncomeLoss
Incremental dilution from VMware	(1)us-gaap_DilutiveSecurities	(2)us-gaap_DilutiveSecurities
Net income – dilution attributable to EMC Corporation	$ 251	$ 390
Denominator:
Weighted average shares, basic	1,974	2,029
Weighted common stock equivalents	22	26
Assumed conversion of the 2013 Notes and associated warrants	0	21
Weighted average shares, diluted	1,996	2,076

Amount of increase (decrease) to net income used for calculating diluted earnings per share (EPS), resulting from the assumed exercise stock options, restrictive stock units (RSUs), convertible preferred stock of an employee stock ownership plan (ESOP), and other dilutive convertible securities.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible debt securities using the if-converted method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Net Income or Loss Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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