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Guarantees (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
Guarantees (Narrative) (Details) - USD ($)	Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2024	Apr. 30, 2023	Jul. 31, 2023
Advanced Filtration Systems, Inc.
Guarantor Obligations
Investment earnings	$ 4,300,000	$ 4,000,000	$ 8,500,000	$ 5,800,000
Unsecured revolving credit facility
Guarantor Obligations
Available credit facilities	63,000,000		63,000,000
Multi-Currency Revolving Credit Facility
Guarantor Obligations
Available credit facilities	17,000,000		17,000,000
Advanced Filtration Systems, Inc.
Guarantor Obligations
AFSI outstanding debt	$ 49,700,000		$ 49,700,000		$ 59,600,000