Segment Information - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended					3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2011 United States	Sep. 30, 2010 United States	Sep. 30, 2011 United States	Sep. 30, 2010 United States	Dec. 31, 2010 United States	Sep. 30, 2011 International Segment	Dec. 31, 2010 International Segment	Sep. 30, 2011 Acquisition By VMware	Jun. 30, 2010 Acquisition By VMware	Sep. 30, 2011 Acquisition By VMware	Dec. 31, 2010 Acquisition By VMware
Acquisition of certain software product technology and related capabilities									$ 175.0
Contingent amounts paid to EMC in accordance with the asset purchase agreement								1.9		14.4	10.6
Minimum percentage of revenue accounted	10.00%	10.00%	10.00%	10.00%
Long-lived assets, excluding financial instruments, deferred tax assets, goodwill and intangible assets	3,393.1		3,393.1		2,936.8
Minimum percentage of Assets accounted	10.00%		10.00%		10.00%
Long-lived assets, excluding financial instruments and deferred tax assets						$ 584.9	$ 600.3