Summary of Significant Accounting Policies (Details 6) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Supplemental Information on Cash Flows
Interest paid	$ 28.3	$ 16.6	$ 17.2
Income taxes paid	24.1	11.4	9.8
Income tax refunds and interest received	$ 23.2	$ 7.2	$ 4.5
Building and improvements | Minimum
Property, Plant and Equipment
Useful life	10 years
Building and improvements | Maximum
Property, Plant and Equipment
Useful life	40 years
Equipment | Minimum
Property, Plant and Equipment
Useful life	3 years
Equipment | Maximum
Property, Plant and Equipment
Useful life	10 years
Furniture and fixtures | Minimum
Property, Plant and Equipment
Useful life	3 years
Furniture and fixtures | Maximum
Property, Plant and Equipment
Useful life	10 years
Capitalized software | Minimum
Property, Plant and Equipment
Useful life	3 years
Capitalized software | Maximum
Property, Plant and Equipment
Useful life	10 years
Aircraft and components | Minimum
Property, Plant and Equipment
Useful life	7 years
Aircraft and components | Maximum
Property, Plant and Equipment
Useful life	20 years