Percentage of Net Product and Engineering Revenue from Major Customers (Detail) - Sales Revenue, Net - Largest customers	12 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Concentration Risk [Line Items]
Percentage of net product and engineering revenue	64.00%	66.00%	68.00%
Philips
Concentration Risk [Line Items]
Percentage of net product and engineering revenue	14.00%	16.00%	15.00%
L-3
Concentration Risk [Line Items]
Percentage of net product and engineering revenue	13.00%	11.00%	12.00%
Toshiba
Concentration Risk [Line Items]
Percentage of net product and engineering revenue	11.00%	12.00%	10.00%
Siemens AG
Concentration Risk [Line Items]
Percentage of net product and engineering revenue	11.00%	11.00%