Accrued Expenses and Other Current Liabilities - Schedule (Details) - USD ($)	Apr. 30, 2020	Jul. 31, 2019	Apr. 30, 2019	Jul. 31, 2018
Accrued Liabilities, Current [Abstract]
Accrued wages and benefits	$ 23,473,000	$ 23,295,000
Accrued contract costs	12,383,000	15,007,000
Accrued warranty obligations	15,504,000	15,968,000	$ 14,263,000	$ 11,738,000
Accrued legal costs	2,880,000	2,835,000
Accrued commissions and royalties	4,131,000	5,114,000
Other	25,190,000	16,365,000
Accrued expenses and other current liabilities	$ 83,561,000	$ 78,584,000