Acquisitions and Divestitures Acquisitions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				3 Months Ended		3 Months Ended		3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2012 Nexsan Corporation	Mar. 31, 2013 MXI Security	Jun. 04, 2011 MXI Security	Mar. 31, 2013 BeCompliant Corporation (Encryptx)	Feb. 28, 2011 BeCompliant Corporation (Encryptx)	Mar. 31, 2013 Cash Flows from Financing Activities BeCompliant Corporation (Encryptx)	Mar. 31, 2013 Cash Flows from Operating Activities BeCompliant Corporation (Encryptx)
Business Acquisition, Contingent Consideration [Line Items]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net				$ 120.1
Goodwill	70.6		73.5	65.5
Goodwill, Purchase Accounting Adjustments	1.6	0
Contingent consideration fair value					0.5	0.6		0.6
Contingent consideration adjustment	(0.1)	0			0.1
Contingent consideration payments	$ 0.5	$ 0.7					$ 0.8		$ 0.5	$ 0.3