Quarterly Results of Operations - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended				12 Months Ended			1 Months Ended	3 Months Ended	12 Months Ended
	Nov. 19, 2010	Jan. 31, 2012	Jul. 31, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010	Jul. 25, 2011 China-based affiliate	Jan. 31, 2012 China-based affiliate	Jul. 31, 2012 China-based affiliate	Jul. 31, 2012 Income Tax Refund
Quarterly Financial Information [Line Items]
Income tax refund received		$ 12,007
Income Tax expense benefit						1,128	4,312	5,668				(10,025)
Professional fees related to refund of Tax						2,714
Gain on sale of other investments						2,500				2,500	2,500
Percentage of interest in affiliate sold									25.00%	25.00%
Value of interest in affiliate									2,500	2,500
Restructuring charge			3,587		3,562		7,066	690
Bargain purchase gain	$ 1,042			$ 1,042			$ 1,042