Fair Value of Major Classes of Tangible and Identifiable Intangible Assets Acquired (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended	12 Months Ended
	Nov. 19, 2010	Jan. 31, 2011	Jul. 31, 2011
Business Acquisition [Line Items]
Inventory	$ 1,284
Property, plant, and equipment	489
Intangible assets	730
Accrued liabilities	(154)
Deferred tax liabilities	(621)
Net tangible and intangible assets	1,728
Estimated purchase price	686
Bargain purchase gain	$ 1,042	$ 1,042	$ 1,042