Severance and Exit Costs (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	9 Months Ended
	Nov. 30, 2011	Feb. 29, 2012	May 31, 2011	Feb. 28, 2011	Nov. 30, 2010	May 31, 2010
Voluntary Retirement Program Severance Expense		$ 9.3
Accrued Severance Cost		1.2	1.9	1.5	1.5	3.4
Loss On Leases	$ 6.2	$ 6.2