Guarantees (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Jul. 31, 2020
Guarantor Obligations
Royalty income	$ 636.6	$ 672.7
Advanced Filtration Systems, Inc.
Guarantor Obligations
Outstanding debt (the Company guarantees half)	38.9		$ 40.0
Contingent liability for standby letters of credit	7.7		7.5
Amounts drawn for letters of credit	0.0		$ 0.0
Investment earnings (loss)	0.4	0.1
Advanced Filtration Systems, Inc. | Royalty
Guarantor Obligations
Royalty income	$ 1.6	$ 1.9