Severance and Exit Costs (Detail) - Schedule of accrued severance cost associated with cost reduction measures (USD $) In Millions, unless otherwise specified	9 Months Ended		12 Months Ended
	Feb. 28, 2013	Feb. 28, 2012	May 31, 2012
Beginning balance	$ 2.7	$ 1.9	$ 1.9
Accruals	5.3	12.2	14.9
Payments	(5.5)	(12.9)	(14.1)
Ending balance	$ 2.5	$ 1.2	$ 2.7