Accrued Severance (Details) - Schedule of accrued severance cost associated with cost reduction measures (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012
Schedule of accrued severance cost associated with cost reduction measures [Abstract]
Beginning balance	$ 2.7	$ 1.9
Accruals	13.4	14.9
Payments	(12.8)	(14.1)
Ending balance	$ 3.3	$ 2.7