Accrued Expenses and Other Current Liabilities (Details) - USD ($)	Jul. 31, 2019	Aug. 01, 2018	Jul. 31, 2018	Jul. 31, 2017
Accrued Liabilities, Current [Abstract]
Accrued wages and benefits	$ 23,295,000		$ 23,936,000
Accrued contract costs	15,007,000		10,016,000
Accrued warranty obligations	15,968,000		11,738,000	$ 17,617,000
Accrued legal costs	2,835,000		6,179,000
Accrued commissions and royalties	5,114,000		4,654,000
Other	16,365,000		8,511,000
Accrued expenses and other current liabilities	$ 78,584,000	$ 62,955,000	$ 65,034,000