Change in Plan Assets (Detail) - USD ($) $ in Millions		12 Months Ended
		Jul. 31, 2017		Jul. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Balance at beginning of fiscal year		$ 15.3	[1]	$ 15.0
Actual return on plan assets		0.9		0.4
Employer contributions				1.0
Plan participant contributions				0.1
Benefits paid		(0.2)		(1.5)
Foreign currency exchange gain		0.7		0.1
Transfer from other plans				0.2
Balance at end of fiscal year	[1]	16.7		15.3
Funded status		(2.3)		(4.0)
Recognized Long-term liability		$ (2.3)		$ (4.0)

[1] This comprises units of segregated pooled funds with an insurance company. These funds have underlying values primarily derived from mutual funds that have debt and equity securities, which are traded on an active market based on the closing price of each trading day.