Guarantees (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020	Jul. 31, 2020
Guarantor Obligations
Royalty income	$ 679.1	$ 662.0	$ 1,315.8	$ 1,334.7
Advanced Filtration Systems, Inc.
Guarantor Obligations
Outstanding debt (the Company guarantees half)	33.7		33.7		$ 40.0
Contingent liability for standby letters of credit	7.7		7.7		7.5
Amounts drawn for letters of credit	0.0		0.0		$ 0.0
Investment earnings	0.2	0.3	0.5	0.4
Advanced Filtration Systems, Inc. | Royalty
Guarantor Obligations
Royalty income	$ 1.7	$ 1.7	$ 3.2	$ 3.6