Commitments and Contingencies (Details) - Schedule for composition of capital leased assets (USD $) In Millions, unless otherwise specified	May 31, 2013	May 31, 2012
Capital Leased Assets [Line Items]
Capital Leased Assets, Gross	$ 40.0	$ 43.5
Accumulated amortization	(13.4)	(12.3)
Total	26.6	31.2
Land [Member]
Capital Leased Assets [Line Items]
Capital Leased Assets, Gross		3.5
Building [Member]
Capital Leased Assets [Line Items]
Capital Leased Assets, Gross	39.0	39.0
Equipment [Member]
Capital Leased Assets [Line Items]
Capital Leased Assets, Gross	$ 1.0	$ 1.0