Restructuring Charges - Reconciliation of Beginning and Ending Restructuring Reserve Balances (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Restructuring Reserve [Roll Forward]
Beginning balance			$ 10.4
Costs incurred and charged to expense	$ 3.9	$ 10.2	8.7	$ 17.9
Costs paid or otherwise settled			(12.1)
Ending balance	7.0		7.0
Employee Separation Costs
Restructuring Reserve [Roll Forward]
Beginning balance			9.2
Costs incurred and charged to expense	2.9		6.8
Costs paid or otherwise settled			(10.0)
Ending balance	6.0		6.0
Other Costs
Restructuring Reserve [Roll Forward]
Beginning balance			1.2
Costs incurred and charged to expense	1.0		1.9
Costs paid or otherwise settled			(2.1)
Ending balance	$ 1.0		$ 1.0