Goodwill and Other Intangibles (Details) - Schedule of activity in goodwill (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012
Schedule of activity in goodwill [Abstract]
Gross beginning balance	$ 178.5	$ 175.0
Accumulated impairment	(20.8)	(20.8)
Beginning balance	157.7	154.2
Additions due to acquisition		2.7
Foreign currency translation	0	0
Other	0.2	0.8
Gross ending balance	178.7	178.5
Accumulated impairment	(20.8)	(20.8)
Ending balance	$ 157.9	$ 157.7