Components of Other Post Retirement Benefit Expenses (Detail) (Other Postretirement Benefits, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2012	May 31, 2011
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1.1	$ 0.8	$ 2.2	$ 1.9
Interest costs	1.2	1.1	2.4	2.2
Amortization of prior service costs	(1.0)	(1.5)	(2.0)	(3.0)
Amortization of losses	0.1	0.1	0.1	0.4
Total other postretirement expense	$ 1.4	$ 0.5	$ 2.7	$ 1.5