Valuation and Qualifying Accounts (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Valuation and Qualifying Accounts Disclosure [Line Items]
Cost of sales	$ 190,473	$ 71,223	$ 63,637
Damages from Product Defects
Valuation and Qualifying Accounts Disclosure [Line Items]
Cost of sales	3,700	1,800	2,400
Reserve for Customer Deductions
Valuation and Qualifying Accounts Disclosure [Line Items]
Cost of sales	$ 2,700	$ 2,800	$ 3,300