Accrued Expenses and Other Current Liabilities (Details) - USD ($)	Jan. 31, 2019	Jul. 31, 2018	Jan. 31, 2018	Jul. 31, 2017
Accrued Liabilities, Current [Abstract]
Accrued wages and benefits	$ 23,239,000	$ 23,936,000
Accrued contract costs	11,202,000	10,016,000
Accrued warranty obligations	9,576,000	11,738,000	$ 12,481,000	$ 17,617,000
Accrued legal costs	2,625,000	6,179,000
Accrued commissions and royalties	3,541,000	4,654,000
Other	10,160,000	8,511,000
Accrued expenses and other current liabilities	$ 60,343,000	$ 65,034,000