Revenue Recognition (Sales by Geography and Customer Type (Details) - Net sales	3 Months Ended
	Oct. 31, 2021	Oct. 31, 2020
Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%
Geographic Concentration Risk | U.S. government
Concentration Risk [Line Items]
Concentration risk, percentage	30.10%	32.50%
Geographic Concentration Risk | Domestic
Concentration Risk [Line Items]
Concentration risk, percentage	48.50%	41.90%
Geographic Concentration Risk | Total United States
Concentration Risk [Line Items]
Concentration risk, percentage	78.60%	74.40%
Geographic Concentration Risk | International
Concentration Risk [Line Items]
Concentration risk, percentage	21.40%	25.60%
Customer Concentration Risk | Verizon Communications Inc.
Concentration Risk [Line Items]
Concentration risk, percentage	11.70%	12.50%