Employee Benefit Plans (Details) - Schedule Of Amounts Recognized In Balance Sheet (USD $) In Millions, unless otherwise specified	May 31, 2013	May 31, 2012
Pension Plan, Defined Benefit [Member]
Employee Benefit Plans (Details) - Schedule Of Amounts Recognized In Balance Sheet [Line Items]
Non-current liabilities	$ 11.8	$ 36.4
Net underfunded balance	11.8	36.4
Other Postretirement Benefit Plan, Defined Benefit [Member]
Employee Benefit Plans (Details) - Schedule Of Amounts Recognized In Balance Sheet [Line Items]
Current liabilities	2.7	3.4
Non-current liabilities	33.5	36.2
Net underfunded balance	$ 36.2	$ 39.6