Percentage of Net Product and Engineering Revenue from Major Customers (Detail) - Sales Revenue, Net - Largest customers	3 Months Ended		9 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Concentration Risk [Line Items]
Percentage of net product and engineering revenue	61.00%	62.00%	63.00%	62.00%
Philips
Concentration Risk [Line Items]
Percentage of net product and engineering revenue	14.00%	14.00%	14.00%	13.00%
Siemens AG
Concentration Risk [Line Items]
Percentage of net product and engineering revenue	11.00%	11.00%	12.00%	13.00%
L-3
Concentration Risk [Line Items]
Percentage of net product and engineering revenue	11.00%	10.00%	10.00%
Toshiba
Concentration Risk [Line Items]
Percentage of net product and engineering revenue				11.00%