Summary of Significant Accounting Policies (Details 6) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2012
Property, Plant and Equipment
Equipment on or available for long-term lease	$ 98.4	$ 64.7
Supplemental Information on Cash Flows
Interest paid	33.8	28.3	16.6
Income taxes paid	17.3	24.1	11.4
Income tax refunds and interest received	7.5	23.2	7.2
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	30 years
Rotable parts
Property, Plant and Equipment
Equipment on or available for long-term lease	73.1	41.7
Aircraft
Property, Plant and Equipment
Equipment on or available for long-term lease	$ 25.3	$ 23.0