Business Combinations, Intangibles and Goodwill - Goodwill (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Goodwill [Roll Forward]
Balance, beginning of the period	$ 13,839,700	$ 12,154,970
Goodwill resulting from acquisitions	162,334	1,724,027
Tax deduction from exercise of stock options		(100)
Finalization of purchase price allocations	(8,122)	(10,003)
Goodwill derecognized in divestiture of business		(29,194)
Balance, end of the period	13,993,912	13,839,700
Information Storage
Goodwill [Roll Forward]
Balance, beginning of the period	7,441,351	7,033,965
Goodwill resulting from acquisitions	0	437,868
Tax deduction from exercise of stock options		(7)
Finalization of purchase price allocations	270	(1,281)
Goodwill derecognized in divestiture of business		(29,194)
Balance, end of the period	7,441,621	7,441,351
Information Intelligence Group
Goodwill [Roll Forward]
Balance, beginning of the period	1,484,220	1,469,216
Goodwill resulting from acquisitions	0	15,097
Tax deduction from exercise of stock options		(93)
Finalization of purchase price allocations	6	0
Goodwill derecognized in divestiture of business		0
Balance, end of the period	1,484,226	1,484,220
RSA Information Security
Goodwill [Roll Forward]
Balance, beginning of the period	2,022,406	1,849,116
Goodwill resulting from acquisitions	0	179,389
Tax deduction from exercise of stock options		0
Finalization of purchase price allocations	(1,003)	(6,099)
Goodwill derecognized in divestiture of business		0
Balance, end of the period	2,021,403	2,022,406
VMware Virtual Infrastructure Within EMC
Goodwill [Roll Forward]
Balance, beginning of the period	2,891,723	1,802,673
Goodwill resulting from acquisitions	162,334	1,091,673
Tax deduction from exercise of stock options		0
Finalization of purchase price allocations	(7,395)	(2,623)
Goodwill derecognized in divestiture of business		0
Balance, end of the period	$ 3,046,662	$ 2,891,723