Accounts Receivable (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jan. 31, 2023	Jul. 31, 2022
Statement [Line Items]
Total accounts receivable	$ 137,725,000	$ 126,048,000
Less allowance for doubtful accounts	2,803,000	2,337,000
Accounts receivable, net	$ 134,922,000	$ 123,711,000
Accounts Receivable | Customer Concentration Risk | U.S. government
Statement [Line Items]
Concentration risk, percentage	21.10%	20.90%
Accounts Receivable | Customer Concentration Risk | AT&T, Inc.
Statement [Line Items]
Concentration risk, percentage	11.90%
Accounts Receivable | Customer Concentration Risk | Verizon
Statement [Line Items]
Concentration risk, percentage	11.60%	13.40%
Billed Receivables | Commercial and International Customers
Statement [Line Items]
Total accounts receivable	$ 63,169,000	$ 59,922,000
Billed Receivables | U.S. Government and Its Agencies
Statement [Line Items]
Total accounts receivable	23,370,000	24,776,000
Unbilled Receivables
Statement [Line Items]
Long-term unbilled receivables	2,584,000
Unbilled Receivables | Commercial and International Customers
Statement [Line Items]
Total accounts receivable	45,450,000	39,826,000
Unbilled Receivables | U.S. Government and Its Agencies
Statement [Line Items]
Total accounts receivable	$ 5,736,000	$ 1,524,000