Severance (Detail) - Schedule of accrued severance (USD $) In Millions	3 Months Ended		12 Months Ended
	Aug. 31, 2011	Aug. 31, 2010	May 31, 2011
Beginning balance	$ 1.9	$ 3.4	$ 3.4
Accruals	3.3	2.1	6.7
Payments	(2.8)	(3.8)	(8.2)
Ending balance	$ 2.4	$ 1.7	$ 1.9