Change in Benefit Obligation (Detail) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Current service cost		$ 0.6	$ 1.3
Interest cost	$ 0.7	0.7	0.7
Transfer from other plans		(0.2)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year	19.3	17.0
Current service cost		0.6
Foreign currency exchange loss	0.8	0.1
Interest cost	0.7	0.7
Net actuarial (gain) loss	(1.6)	2.1
Plan participant contributions		0.1
Benefit payments	(0.2)	(1.5)
Transfer from other plans		0.2
Balance at end of year	$ 19.0	$ 19.3	$ 17.0