Income Taxes	6 Months Ended
Jun. 30, 2012
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our effective income tax rates were 23.7% and 23.5% for the three and six months ended June 30, 2012, respectively. Our effective income tax rates were 22.6% and 21.2% for the three and six months ended June 30, 2011, respectively. Our effective income tax rate is based upon estimated income before tax for the year, composition of the income in different countries, and adjustments, if any, in the applicable quarterly periods for potential tax consequences, benefits and/or resolutions of tax audits or other tax contingencies. For the three and six months ended June 30, 2012 and 2011, the effective income tax rate varied from the statutory income tax rate principally as a result of the mix of income attributable to foreign versus domestic jurisdictions. Our aggregate income tax rate in foreign jurisdictions is lower than our income tax rate in the United States; substantially all of our income before provision for income taxes from foreign operations has been earned by our Irish subsidiaries. We do not believe that any recent or currently expected developments in non-U.S. tax jurisdictions are reasonably likely to have a material impact on our effective income rate. Our effective income tax rate increased in the three and six months ended June 30, 2012 from the three and six months ended June 30, 2011 due primarily to the expiration of the U.S. federal research and development tax credit for 2012. The U.S. federal research and development tax credit reduced our effective income tax rate by approximately 1.8% for the three and six months ended June 30, 2011. There were also differences in composition of income before tax in different countries, change in tax contingency reserves and discrete items, the net impact of which is immaterial. During the three months ended June 30, 2012, we determined that since VMware’s initial public offering in 2007, we have incorrectly recorded deferred tax liabilities on the gains and losses associated with changes in the non-controlling interest. These deferred tax liabilities were recorded as a reduction to additional paid-in capital and therefore had no impact on our previously reported consolidated income statements. The error resulted in an overstatement of our deferred tax liability and an understatement of our additional paid-in capital of $352.6 million in our December 31, 2011 consolidated balance sheet and an understatement of additional paid-in capital of $407.2 million in our statement of shareholders’ equity for the six months ended June 30, 2011. These corrections did not impact our income tax provision in any current or prior period. See Note 1. We are routinely under audit by the Internal Revenue Service (the “IRS”). We have concluded all U.S. federal income tax matters for years through 2008. The IRS is expected to commence a federal income tax audit for the tax years of 2009 and 2010 in the third quarter of 2012. We also have income tax audits in process in numerous state, local and international jurisdictions. Based on the timing and outcome of examinations of EMC, the result of the expiration of statutes of limitations for specific jurisdictions and/or the timing and result of ruling requests from taxing authorities, it is reasonably possible that the related unrecognized tax benefits could change from those recorded in our statement of financial position. We anticipate that several of these audits may be finalized within the next 12 months. Based on the status of these examinations, and the protocol of finalizing such audits, it is not possible to estimate the impact of the amount of such changes, if any, to our previously recorded uncertain tax positions.

Income Taxes

Our effective income tax rates were 23.7% and 23.5% for the three and six months ended June 30, 2012, respectively. Our effective income tax rates were 22.6% and 21.2% for the three and six months ended June 30, 2011, respectively. Our effective income tax rate is based upon estimated income before tax for the year, composition of the income in different countries, and adjustments, if any, in the applicable quarterly periods for potential tax consequences, benefits and/or resolutions of tax audits or other tax contingencies. For the three and six months ended June 30, 2012 and 2011, the effective income tax rate varied from the statutory income tax rate principally as a result of the mix of income attributable to foreign versus domestic jurisdictions. Our aggregate income tax rate in foreign jurisdictions is lower than our income tax rate in the United States; substantially all of our income before provision for income taxes from foreign operations has been earned by our Irish subsidiaries. We do not believe that any recent or currently expected developments in non-U.S. tax jurisdictions are reasonably likely to have a material impact on our effective income rate.

Our effective income tax rate increased in the three and six months ended June 30, 2012 from the three and six months ended June 30, 2011 due primarily to the expiration of the U.S. federal research and development tax credit for 2012. The U.S. federal research and development tax credit reduced our effective income tax rate by approximately 1.8% for the three and six months ended June 30, 2011. There were also differences in composition of income before tax in different countries, change in tax contingency reserves and discrete items, the net impact of which is immaterial.

During the three months ended June 30, 2012, we determined that since VMware’s initial public offering in 2007, we have incorrectly recorded deferred tax liabilities on the gains and losses associated with changes in the non-controlling interest. These deferred tax liabilities were recorded as a reduction to additional paid-in capital and therefore had no impact on our previously reported consolidated income statements. The error resulted in an overstatement of our deferred tax liability and an understatement of our additional paid-in capital of $352.6 million in our December 31, 2011 consolidated balance sheet and an understatement of additional paid-in capital of $407.2 million in our statement of shareholders’ equity for the six months ended June 30, 2011. These corrections did not impact our income tax provision in any current or prior period. See Note 1.

We are routinely under audit by the Internal Revenue Service (the “IRS”). We have concluded all U.S. federal income tax matters for years through 2008. The IRS is expected to commence a federal income tax audit for the tax years of 2009 and 2010 in the third quarter of 2012. We also have income tax audits in process in numerous state, local and international jurisdictions. Based on the timing and outcome of examinations of EMC, the result of the expiration of statutes of limitations for specific jurisdictions and/or the timing and result of ruling requests from taxing authorities, it is reasonably possible that the related unrecognized tax benefits could change from those recorded in our statement of financial position. We anticipate that several of these audits may be finalized within the next 12 months. Based on the status of these examinations, and the protocol of finalizing such audits, it is not possible to estimate the impact of the amount of such changes, if any, to our previously recorded uncertain tax positions.