Discontinued Operations - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	May 06, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration received for sale of ESG business	$ 480,000,000
Date of completion of sale of business		May 06, 2011
Income from discontinued operations		0	241,479,000	5,568,000
Restructuring expenses related to the exit of the ESG business			40,900,000	49,700,000
Released deferred tax liabilities related to sale of external storage systems business			21,000,000
(Benefit from)/provision for income taxes			(8,992,000)	2,250,000
Stock based compensation expense benefit of ESG Business			600,000
Stock base compensation expense related to ESG Business				$ 12,400,000