Post Retirement Benefit Plans - Components of Net Periodic Cost for Postretirement Benefits (Details) - Other Postretirement Benefits Plan - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 0.5	$ 0.5	$ 0.5
Amortization of prior service (cost) benefit	(1.3)	(1.4)	(1.4)
Recognized net actuarial gain	(0.3)	(0.2)	(0.2)
Net periodic pension (benefit) cost	$ (1.1)	$ (1.1)	$ (1.1)