Post Retirement Benefit Plans - Components of Net Periodic Cost for Postretirement Benefits (Detail) - Other Postretirement Benefit Plans, Defined Benefit - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Interest cost	0.1	0.2	0.3	0.4
Amortization of prior service cost and net actuarial gain	(0.5)	(0.4)	(1.2)	(1.2)
Net periodic costs (benefits) for pension and postretirement benefits	$ (0.4)	$ (0.2)	$ (0.9)	$ (0.8)