Post Retirement Benefit Plans - Components of Net Periodic Cost for Postretirement Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Recognized net actuarial gain	$ 1.3	$ 27.1	$ 0.0
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0.5	0.5	0.5
Amortization of prior service cost	(1.4)	(1.4)	(1.5)
Recognized net actuarial gain	(0.2)	(0.2)	(0.1)
Net periodic pension (benefit) cost	$ (1.1)	$ (1.1)	$ (1.1)