Valuation And Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 0.8	$ 0.6	$ 0.3
Charged to Costs and Expenses	0.4	0.2	0.4
Deductions			(0.1)
Balance at End of Period	1.2	0.8	0.6
Income Tax Valuation Allowance
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	6.6	6.3	5.5
Charged to Costs and Expenses	4.3	0.4	0.8
Deductions	(0.3)	(0.1)
Balance at End of Period	$ 10.6	$ 6.6	$ 6.3