Post Retirement Benefit Plans - Components of Net Periodic Pension Cost (Detail) - Pension Plans, Defined Benefit - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3.3	$ 3.1	$ 6.6	$ 6.2
Interest cost	4.6	5.6	9.2	11.2
Expected return on plan assets	(7.1)	(8.3)	(14.2)	(16.6)
Amortization of prior service cost and net actuarial gain	2.8	2.9	5.6	5.8
Net periodic costs (benefits) for pension and postretirement benefits	$ 3.6	$ 3.3	$ 7.2	$ 6.6