Commitments and Guarantees - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended			12 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended	1 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012	Jul. 31, 2012	Jul. 31, 2012 Minimum	Jan. 31, 2013 Maximum	Jan. 31, 2012 Maximum	Jan. 31, 2013 Maximum	Jan. 31, 2012 Maximum	Jul. 31, 2012 Maximum	Oct. 11, 2011 Credit Agreement	Jan. 31, 2013 Credit Agreement	Jul. 31, 2012 Credit Agreement	Jan. 31, 2013 Credit Agreement Other Revolving Credit Facilities	Jan. 31, 2013 Product Extended Warranty Contracts	Jul. 31, 2012 Product Extended Warranty Contracts
Commitments and Contingencies Disclosure [Line Items]
Standard product warranty term						12 months					26 months
Deferred revenue for product extended warranty contracts	$ 11,789		$ 11,789		$ 12,267											$ 7,075	$ 7,207
Credit facility maximum borrow capacity												100,000
Number of banks												3
Revolving credit agreement period												5 years
Credit agreement expiry date												Oct. 10, 2016
Aggregate available credit amount under specified circumstances												150,000
Percentage of capital stock pledge as collateral												65.00%
Credit facility available borrow capacity															4,000
Line of credit amount outstanding													0	0
Percentage of revenue							0.30%	2.50%	0.30%	2.50%
Employee termination costs				400
Business exit cost	$ 330	$ 207	$ 405	$ 1,204