Restructuring and Voluntary Retirement Charges - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended		3 Months Ended		12 Months Ended		3 Months Ended	12 Months Ended
	Jul. 31, 2011 Person	Oct. 31, 2010 Person	Jan. 31, 2010 Person	Jul. 31, 2011	Jul. 31, 2010	Jan. 31, 2011 Involuntary Employee Severance	Jul. 31, 2010 Involuntary Employee Severance	Jul. 31, 2011 Involuntary Employee Severance	Jul. 31, 2010 Involuntary Employee Severance	Jul. 31, 2010 Facility Exit Costs	Jul. 31, 2011 Facility Exit Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charge	$ 3,587	$ 3,562		$ 7,066	$ 690				$ 764	$ 420
Reduction in workforce	51	104	17
Adjustments				$ (81)	$ (494)	$ 134	$ 494	$ (134)	$ (494)		$ 53