Income Taxes	9 Months Ended
Sep. 30, 2013
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our effective income tax rates were 22.1% and 19.1% for the three and nine months ended September 30, 2013, respectively. Our effective income tax rates were 22.0% and 23.0% for the three and nine months ended September 30, 2012, respectively. Our effective income tax rate is based upon estimated income before provision for income taxes 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 nine months ended September 30, 2013, 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, state taxes and the federal tax credit for increasing research activities. 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. On January 2, 2013, the American Taxpayer Relief Act of 2012 was signed into law. Some of the provisions were retroactive to January 1, 2012 including an extension of the U.S. federal tax credit for increasing research activities through December 31, 2013. Because the extension was enacted after December 31, 2012, our income tax provision for the nine months ended September 30, 2013 included the federal tax credit for increasing research activities for the full year 2012 as well as the nine months ended September 30, 2013, which reduced our effective tax rate for the nine month period. For the three and nine months ended September 30, 2012, 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 effective income tax rate decreased in the nine months ended September 30, 2013 from the nine months ended September 30, 2012 due primarily to the retroactive renewal of the U.S. federal tax credit for increasing research activities on January 2, 2013 as discussed above. The U.S. federal tax credit for increasing research activities reduced our effective income tax rate by approximately 4.4% for the nine months ended September 30, 2013. There were also differences in the mix of income attributable to foreign versus domestic jurisdictions, state taxes, change in tax contingency reserves and discrete items, the net impact of which is immaterial. Our effective income tax rate for the three months ended September 30, 2013 is consistent with our effective income tax rate for the three months ended September 30, 2012 as a 3.0% favorable impact of U.S. federal tax credit for increasing research activities on our effective income tax rate is offset by a lower estimated Section 199 deduction and other differences between the two three-month periods. 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 commenced a federal income tax audit for the tax years 2009 and 2010 in the third quarter of 2012. The current federal income tax audit is still in the early stage for information gathering and it is not expected to be completed until 2015. We also have income tax audits in process in numerous state, local and international jurisdictions. In our international jurisdictions that comprise a significant portion of our operations, the years that may be examined vary, with the earliest year being 2003. Based on the timing and outcome of examinations of EMC, the result of the expiration of statutes of limitations for specific jurisdictions 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 twelve months. While we expect the amount of unrecognized tax benefits to change in the next twelve months, we do not expect the change to have a significant impact on our results of operations or financial position.

Income Taxes

Our effective income tax rates were 22.1% and 19.1% for the three and nine months ended September 30, 2013, respectively. Our effective income tax rates were 22.0% and 23.0% for the three and nine months ended September 30, 2012, respectively. Our effective income tax rate is based upon estimated income before provision for income taxes 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 nine months ended September 30, 2013, 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, state taxes and the federal tax credit for increasing research activities. 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. On January 2, 2013, the American Taxpayer Relief Act of 2012 was signed into law. Some of the provisions were retroactive to January 1, 2012 including an extension of the U.S. federal tax credit for increasing research activities through December 31, 2013. Because the extension was enacted after December 31, 2012, our income tax provision for the nine months ended September 30, 2013 included the federal tax credit for increasing research activities for the full year 2012 as well as the nine months ended September 30, 2013, which reduced our effective tax rate for the nine month period. For the three and nine months ended September 30, 2012, 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 effective income tax rate decreased in the nine months ended September 30, 2013 from the nine months ended September 30, 2012 due primarily to the retroactive renewal of the U.S. federal tax credit for increasing research activities on January 2, 2013 as discussed above. The U.S. federal tax credit for increasing research activities reduced our effective income tax rate by approximately 4.4% for the nine months ended September 30, 2013. There were also differences in the mix of income attributable to foreign versus domestic jurisdictions, state taxes, change in tax contingency reserves and discrete items, the net impact of which is immaterial. Our effective income tax rate for the three months ended September 30, 2013 is consistent with our effective income tax rate for the three months ended September 30, 2012 as a 3.0% favorable impact of U.S. federal tax credit for increasing research activities on our effective income tax rate is offset by a lower estimated Section 199 deduction and other differences between the two three-month periods.

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 commenced a federal income tax audit for the tax years 2009 and 2010 in the third quarter of 2012. The current federal income tax audit is still in the early stage for information gathering and it is not expected to be completed until 2015. We also have income tax audits in process in numerous state, local and international jurisdictions. In our international jurisdictions that comprise a significant portion of our operations, the years that may be examined vary, with the earliest year being 2003. Based on the timing and outcome of examinations of EMC, the result of the expiration of statutes of limitations for specific jurisdictions 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 twelve months. While we expect the amount of unrecognized tax benefits to change in the next twelve months, we do not expect the change to have a significant impact on our results of operations or financial position.