Accounts Receivable (Details) - USD ($)	12 Months Ended
	Jul. 31, 2022	Jul. 31, 2021
Statement [Line Items]
Total accounts receivable	$ 126,048,000	$ 159,758,000
Less: Allowance for doubtful accounts	2,337,000	1,648,000
Accounts receivable, net	$ 123,711,000	$ 158,110,000
U.S. Government and Its Agencies | Accounts Receivable | Customer Concentration Risk
Statement [Line Items]
Concentration risk, percentage	20.90%	23.00%
AT&T, Inc. | Accounts Receivable | Customer Concentration Risk
Statement [Line Items]
Concentration risk, percentage		12.70%
Verizon Communications Inc. | Accounts Receivable | Customer Concentration Risk
Statement [Line Items]
Concentration risk, percentage	13.40%	12.10%
Billed Receivables | Commercial and International Customers
Statement [Line Items]
Total accounts receivable	$ 59,922,000	$ 86,890,000
Billed Receivables | U.S. Government and Its Agencies
Statement [Line Items]
Total accounts receivable	24,776,000	33,381,000
Unbilled Receivables | Commercial and International Customers
Statement [Line Items]
Total accounts receivable	39,826,000	36,131,000
Unbilled Receivables | U.S. Government and Its Agencies
Statement [Line Items]
Total accounts receivable	$ 1,524,000	$ 3,356,000