Joint Ventures (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended
	Apr. 30, 2012	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Equity Method Investment Description Of Principal Activities		VCE, through Vblock infrastructure platforms, delivers an integrated IT offering that combines network, computing, storage, management, security and virtualization technologies for converged infrastructures and cloud based computing models.
Accumulated capital contribution		$ 447.0
Capital contribution	94.7
Accumulated stock-based compensation contributed to joint venture		11.7
Consolidated ownership perentage of outstanding equity		58.00%
Consolidated share of losses		63.20%	58.00%
Net Accumulated Loss from VCE		308.8
Loss From VCE		55.5	41.9
Revenue recognized from sales to VCE		58.4	22.3
Receivable from joint venture		$ 26.3		$ 27.0