Accumulated Other Comprehensive Loss, Net of Tax (Parenthetical) (Detail) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Unrealized losses on temporarily impaired investments, tax benefits	$ (3,850,000)	$ (8,492,000)
Unrealized gains on investments, taxes	28,396,000	18,343,000
Unrealized gains (losses) on derivatives, taxes (benefits)	(56,287,000)	(62,210,000)
Recognition of actuarial net loss from pension and other postretirement plans, tax benefits	$ (81,798,000)	$ (81,798,000)

The tax effect from the total of net (gain) loss, prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

No definition available.

Name:	emc_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansTax
Namespace Prefix:	emc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant