Valuation And Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 1.2	$ 0.8	$ 0.6
Charged to Costs and Expenses	0.1	0.4	0.2
Deductions	(0.3)
Balance at End of Period	1.0	1.2	0.8
Income Tax Valuation Allowance
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	10.6	6.6	6.3
Charged to Costs and Expenses	0.9	4.3	0.4
Deductions		(0.3)	(0.1)
Balance at End of Period	$ 11.5	$ 10.6	$ 6.6