Accounting Policies - Change in the Allowance for Uncollectible Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2018
Accounting Policies [Abstract]
Beginning balance	$ 0.7	$ 1.3	$ 1.1
Net recorded expense	1.3	0.2	0.6
Write-offs, net of recoveries/payments	(0.2)	(0.8)	(0.4)
Ending balance	$ 1.8	$ 0.7	$ 1.3