Post Retirement Benefit Plans - Components of Net Periodic Cost for Postretirement Benefits (Detail) (Other Postretirement Benefit Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2010
Other Postretirement Benefit Plans, Defined Benefit [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Service cost
Interest cost	1.1	1.2	1.6
Amortization of prior service cost	(1.6)	(1.6)	(1.3)
Recognized net actuarial loss (gain)	(0.2)	(0.8)	(0.1)
Net periodic pension cost	$ (0.5)	$ (0.5)	$ 0.2