Goodwill and Other Intangibles (Details) - Schedule of other intangible assets subject to amortization (Parentheticals) (USD $) In Millions, unless otherwise specified	Nov. 30, 2013	May 31, 2013	Nov. 30, 2012
Customer Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Accumulated amortization	$ 2.7	$ 2.3	$ 1.8
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Accumulated amortization	$ 12.7	$ 12.0	$ 11.3