Summary of Charges Related to Accrued Restructuring Activities (Detail) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
		Jan. 31, 2017	Jan. 31, 2017
Restructuring Cost and Reserve [Line Items]
Balance at beginning period		$ 2.5	$ 5.2
Restructuring charge		0.5	0.5
Adjustments		(0.2)	(0.2)
Cash payments		(1.3)	(4.0)
Balance at end period		1.5	1.5
Employee Severance and Benefits
Restructuring Cost and Reserve [Line Items]
Balance at beginning period	[1]	2.5	5.2
Restructuring charge	[1]	0.5	0.5
Adjustments	[1]	(0.2)	(0.2)
Cash payments	[1]	(1.3)	(4.0)
Balance at end period	[1]	$ 1.5	$ 1.5

[1] Restructuring charges in fiscal year 2017 includes $0.5 million with respect to Fiscal Year 2017 actions. All other activity pertains to the Fiscal Year 2016 Restructuring Plan.