Major Customers Who Accounted for 10% or More of Net Product and Engineering Revenue (Detail)	3 Months Ended		9 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012
Product Information [Line Items]
Percentage of net product and engineering revenue	67.00%	72.00%	68.00%	67.00%
Philips
Product Information [Line Items]
Percentage of net product and engineering revenue	14.00%	16.00%	14.00%	16.00%
L-3
Product Information [Line Items]
Percentage of net product and engineering revenue	13.00%	11.00%	12.00%
Toshiba
Product Information [Line Items]
Percentage of net product and engineering revenue			11.00%	10.00%
Siemens Ag
Product Information [Line Items]
Percentage of net product and engineering revenue	11.00%	11.00%		11.00%