Accounts Receivable (Details) - USD ($)	3 Months Ended	6 Months Ended
	Oct. 31, 2024	Jan. 31, 2025	Jul. 31, 2024
Statement [Line Items]
Total accounts receivable		$ 186,990,000	$ 197,527,000
Less allowance for doubtful accounts		19,793,000	1,932,000
Accounts receivable, net		167,197,000	195,595,000
Unbilled receivables, not billable		18,993,000
Cumulative earnings (deficit)		(1,551,000)
Accounts Receivable
Statement [Line Items]
Unbilled receivables, not billable		17,442,000
Modular Transportable Transmission Systems
Statement [Line Items]
Cumulative earnings (deficit)		1,004,000
CGC Divestiture
Statement [Line Items]
Unbilled receivables, not billable		3,003,000
Cumulative earnings (deficit)		4,157,000
Nonrecurring Engineering Projects
Statement [Line Items]
Unbilled receivables, not billable		1,585,000
Cumulative earnings (deficit)		$ 1,752,000
Accounts Receivable | Customer Concentration Risk | U.S. government
Statement [Line Items]
Concentration risk, percentage	36.40%	34.60%
Accounts Receivable | Customer Concentration Risk | AT&T, Inc.
Statement [Line Items]
Concentration risk, percentage	10.90%
Accounts Receivable | Customer Concentration Risk | U.K.
Statement [Line Items]
Concentration risk, percentage	11.30%	13.30%
Billed Receivables | Commercial and International Customers
Statement [Line Items]
Total accounts receivable		$ 58,599,000	53,108,000
Billed Receivables | U.S. Government and Its Agencies
Statement [Line Items]
Total accounts receivable		42,259,000	20,682,000
Unbilled Receivables
Statement [Line Items]
Long-term receivables			824,000
Unbilled Receivables | Commercial and International Customers
Statement [Line Items]
Total accounts receivable		63,679,000	72,540,000
Unbilled Receivables | U.S. Government and Its Agencies
Statement [Line Items]
Total accounts receivable		$ 22,453,000	$ 51,197,000