Severance and Exit Costs (Detail) - Schedule of accrued severance cost associated with cost reduction measures (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Nov. 30, 2012	Nov. 30, 2011	May 31, 2012
Beginning balance	$ 2.7	$ 1.9	$ 1.9
Accruals	2.1	8.3	14.9
Payments	(2.9)	(7.8)	(14.1)
Ending balance	$ 1.9	$ 2.4	$ 2.7