Summary of Net Accounts Receivable Greater Than or Equal to 10% of Net Account Receivable Balance (Detail) (Accounts Receivable, Credit Concentration Risk) (Detail) - Accounts Receivable - Credit Concentration Risk	3 Months Ended	12 Months Ended
	Oct. 31, 2015	Jul. 31, 2015
L-3 Communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of net accounts receivable	10.00%	17.00%
Philips
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of net accounts receivable	13.00%	16.00%
Toshiba
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of net accounts receivable	10.00%		[1]

[1] Total net accounts receivable due from customer was less than 10% in this period.