Restructuring Charges - Reconciliation of Beginning and Ending Restructuring Reserve Balances (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Restructuring Reserve [Roll Forward]
Beginning balance			$ 10.4
Costs incurred and charged to expense	$ 5.1	$ 5.4	4.8	$ 7.7
Costs paid or otherwise settled			(7.1)
Ending balance	8.1		8.1
Employee Separation Costs
Restructuring Reserve [Roll Forward]
Beginning balance			9.2
Costs incurred and charged to expense	4.7		3.9
Costs paid or otherwise settled			(6.2)
Ending balance	6.9		6.9
Other Costs
Restructuring Reserve [Roll Forward]
Beginning balance			1.2
Costs incurred and charged to expense	0.4		0.9
Costs paid or otherwise settled			(0.9)
Ending balance	$ 1.2		$ 1.2