Related Party Transactions - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended			1 Months Ended	3 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2010	Jul. 31, 2011	Jul. 25, 2011 China-based affiliate	Jan. 31, 2012 China-based affiliate	Jul. 31, 2012 China-based affiliate	Jul. 31, 2011 China-based affiliate	Jul. 31, 2010 China-based affiliate	Jul. 31, 2006 China-based affiliate	Apr. 30, 2010 Start-up company	Jul. 31, 2012 Start-up company	Jul. 31, 2011 Start-up company	Jul. 31, 2010 Start-up company
Related Party Transaction [Line Items]
Percentage of interest in affiliate sold				25.00%	25.00%
Value of interest in affiliate				$ 2,500	$ 2,500
Book value of interest in affiliate written down									0
Gain on sale of other investments	2,500				2,500	2,500
Advance payments and deferred revenue	14,323		9,249				474
Sales to affiliate						0	2,808	1,289
Investment in start-up company		1,920								1,900
Received from engineering services from start-up company											$ 1,547	$ 2,438	$ 438