Retirement Plan Benefits - Additional Information (Details) (USD $)	12 Months Ended					60 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Maximum	Dec. 31, 2012 EMC	Dec. 31, 2012 EMC Maximum
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution percentage				6.00%
Employer matching contribution, amount per quarter				$ 750
Percentage of employer matching contributions that are immediately vested	100.00%
Amount of contributions made by employer	88,300,000	73,200,000	34,300,000
Deferred compensation program limit for employee's investment allocation in the company stock fund						30.00%
Fair value of company stock fund held by Pension Plan	430,703,000	395,859,000	379,617,000		500,000
Under-funded status of Pension Plan	108,600,000	86,800,000
Accumulated actuarial loss and prior services cost reclassified from accumulated comprehensive loss to a component of net periodic benefit cost		12,800,000
Pension Plans net losses, primarily the result of a decrease in the discount rate at the end of 2011		26,400,000
Total balance included in accumulated other comprehensive loss that will be recognized as a component of net periodic benefit cost in 2013		$ 14,100,000
Concentration risk, percentage of Pension Plan net assets	5.00%	5.00%