Guarantees (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Guarantor Obligations [Line Items]
Letters of Credit Contingent Liability	$ 0.0	$ 0.0
Letters of Credit Contingent Liability	7.3	7.8
Advanced Filtration Systems Inc.
Guarantor Obligations [Line Items]
Long-term Debt, Gross	24.8
Equity Method Investment, Equity In Earnings	(0.7)	2.3	$ 3.7
Royalty Revenue	$ 5.1	$ 5.8	$ 6.8