Summary of Significant Accounting and Reporting Policies (Narrative) (Details) - USD ($)	12 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Net sales from firm fixed-price contracts as a percentage of consolidated U.S. government net sales	82.60%
Net sales from cost-reimbursable contracts as a percentage of consolidated U.S. government net sales	17.40%
Cash and cash equivalents	$ 150,953,000	$ 154,500,000	$ 356,642,000	$ 367,894,000
Research and development expenses reimbursed by customers	$ 9,229,000	13,103,000	$ 5,172,000
Measurement of uncertain tax position, percentage that likelihood of tax benefit being realized upon ultimate settlement must be greater than	50.00%
Amount invested in money market mutual funds disclosed at fair value.	$ 3,130,000	$ 4,628,000
Minimum [Member]
Machinery and equipment, estimated useful lives	3 years
Maximum [Member]
Machinery and equipment, estimated useful lives	8 years