Joint Ventures (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
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	$ 432.0
Accumulated stock-based compensation contributed to joint venture	9.0
Consolidated ownership perentage of outstanding equity	58.00%
Consolidated share of losses	63.20%	58.00%	58.00%
Net Accumulated Loss from VCE	253.8
Loss From VCE	209.2	43.0	1.6
Revenue recognized from sales to VCE	133.9	0	0
Receivable from joint venture	$ 27.0	$ 19.9