Discontinued Operations (Details) (USD $)	0 Months Ended	12 Months Ended
	May 06, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income from discontinued operations for the external storage systems business
Revenues		$ 210,591,000	$ 700,393,000	$ 642,778,000
(Loss)/income before income taxes and gain on disposal		(27,579,000)	7,818,000	38,794,000
Gain on disposal of ESG business		260,066,000	0	0
(Benefit from)/provision for income taxes		(8,992,000)	2,250,000	26,210,000
Income from discontinued operations		241,479,000	5,568,000	12,584,000
Write down of assets associated with discontinued operations		23,000,000	44,100,000
Discontinued Operations (Textual) [Abstract]
Period to provide certain transitional services as part of asset purchase agreement		Up to eighteen months
Cash consideration received for sale of ESG business	480,000,000
Released deferred tax liabilities related to sale of external storage systems business		21,000,000
Identified intangible assets		10,500,000	17,100,000
Current technology [Member]
Discontinued Operations (Textual) [Abstract]
Identified intangible assets		9,000,000	16,800,000
Customer base [Member]
Discontinued Operations (Textual) [Abstract]
Identified intangible assets		700,000
IPR&D [Member]
Discontinued Operations (Textual) [Abstract]
Identified intangible assets		800,000
Trade names [Member]
Discontinued Operations (Textual) [Abstract]
Identified intangible assets			300,000
Capitalized Software [Member]
Income from discontinued operations for the external storage systems business
Write down of assets associated with discontinued operations		7,800,000	25,400,000
Inventories and fixed assets [Member]
Income from discontinued operations for the external storage systems business
Write down of assets associated with discontinued operations		$ 3,700,000