Restructuring Charges - Reconciliation of Beginning and Ending Restructuring Reserve Balances (Detail) - USD ($) $ in Millions	3 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Restructuring Reserve [Roll Forward]
Beginning balance	$ 5.2
Costs incurred and charged to expense	4.1	$ (0.3)
Costs paid or otherwise settled	(4.5)
Ending balance	4.8
Employee Separation Costs
Restructuring Reserve [Roll Forward]
Beginning balance	3.9
Costs incurred and charged to expense	2.8
Costs paid or otherwise settled	(3.1)
Ending balance	3.6
Other Costs
Restructuring Reserve [Roll Forward]
Beginning balance	1.3
Costs incurred and charged to expense	1.3
Costs paid or otherwise settled	(1.4)
Ending balance	$ 1.2