Net Periodic Benefit Cost (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1.1	$ 1.4	$ 1.1
Interest cost	0.6	0.6	0.6
Expected return on plan assets	(0.8)	(0.7)	(0.7)
Amortization of net actuarial loss recognized	0.1	0.4	0.2
Total net periodic benefit cost	$ 1.0	$ 1.7	$ 1.2