Severance and Exit Costs (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	May 31, 2012	May 31, 2011
Severance	$ 1.3	$ 3.3	$ 14.9
Accrued Severance Cost	$ 1.1	$ 2.4	$ 2.7	$ 1.9