Summary of Preliminary Fair Value Assigned to Net Assets Acquired (Detail) - USD ($) $ in Thousands		12 Months Ended
	May. 01, 2015	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Business Acquisition [Line Items]
Goodwill		$ 312,622	$ 256,579	$ 238,103
Total cash consideration for acquisition, less cash acquired		$ 194,486	$ 86,092	$ 10,718
Postle Operating, LLC
Business Acquisition [Line Items]
Cash	$ 2,963
Other current assets	54,780
Property, plant and equipment	32,251
Goodwill	42,871
Current liabilities	(23,729)
Capital lease obligations	(7,225)
Total fair value of net assets acquired	147,011
Less cash acquired	(2,963)
Total cash consideration for acquisition, less cash acquired	144,048
Postle Operating, LLC | Customer Relationships
Business Acquisition [Line Items]
Business acquisition allocated to amortizing intangible asset	38,800
Postle Operating, LLC | Trademarks
Business Acquisition [Line Items]
Business acquisition allocated to amortizing intangible asset	6,000
Postle Operating, LLC | Backlog
Business Acquisition [Line Items]
Business acquisition allocated to amortizing intangible asset	$ 300