Changes in Carrying Amount of Goodwill (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Goodwill [Line Items]
Balance, beginning of the year	$ 11,772,650,000	$ 9,210,376,000
Goodwill acquired	375,840,000	2,605,926,000
Tax deduction from exercise of stock options	(1,020,000)	(4,075,000)
Other adjustments		0
Finalization of purchase price allocations	7,500,000	(39,577,000)
Balance, end of the year	12,154,970,000	11,772,650,000
Information Storage
Goodwill [Line Items]
Balance, beginning of the year	7,029,341,000	5,045,086,000
Goodwill acquired	0	2,287,712,000
Tax deduction from exercise of stock options	(73,000)	(548,000)
Other adjustments		(275,405,000)
Finalization of purchase price allocations	4,697,000	(27,504,000)
Balance, end of the year	7,033,965,000	7,029,341,000
Information Intelligence Group
Goodwill [Line Items]
Balance, beginning of the year	1,467,903,000	1,476,520,000
Goodwill acquired	0	0
Tax deduction from exercise of stock options	(852,000)	(2,424,000)
Other adjustments		0
Finalization of purchase price allocations	2,165,000	(6,193,000)
Balance, end of the year	1,469,216,000	1,467,903,000
RSA Information Security
Goodwill [Line Items]
Balance, beginning of the year	1,663,213,000	1,529,408,000
Goodwill acquired	187,445,000	140,013,000
Tax deduction from exercise of stock options	(95,000)	(1,103,000)
Other adjustments		0
Finalization of purchase price allocations	(1,447,000)	(5,105,000)
Balance, end of the year	1,849,116,000	1,663,213,000
VMware Virtual Infrastructure Within EMC
Goodwill [Line Items]
Balance, beginning of the year	1,612,193,000	1,159,362,000
Goodwill acquired	188,395,000	178,201,000
Tax deduction from exercise of stock options	0	0
Other adjustments		275,405,000
Finalization of purchase price allocations	2,085,000	(775,000)
Balance, end of the year	$ 1,802,673,000	$ 1,612,193,000