Assets and Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Millions, unless otherwise specified	Apr. 30, 2015	Jul. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Plan assets for deferred compensation	$ 4.2	$ 3.6
Total assets at fair value	4.2	3.6
Contingent consideration	2.0	2.1
Foreign currency forward contracts	0.1
Total liabilities at fair value	2.1	2.1
Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Plan assets for deferred compensation	4.2	3.6
Total assets at fair value	4.2	3.6
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forward contracts	0.1
Total liabilities at fair value	0.1
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	2.0	2.1
Total liabilities at fair value	$ 2.0	$ 2.1