Valuation And Qualifying Accounts (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 0.6	$ 0.3	$ 0.6
Charged to Costs and Expenses	0.2	0.4	0.2
Deductions		(0.1)	(0.5)
Balance at End of Period	0.8	0.6	0.3
Income Tax Valuation Allowance
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	6.3	5.5	5.2
Charged to Costs and Expenses	0.4	0.8	0.5
Deductions	(0.1)		(0.2)
Balance at End of Period	$ 6.6	$ 6.3	$ 5.5