Program Development Costs (Details) (USD $) In Millions, unless otherwise specified	Nov. 30, 2013	May 31, 2013
Program Development Costs
Expected revenue from cargo loading system program	$ 250
Net costs capitalized associated with the engineering and development of the cargo system	129.5	130.9
Net costs capitalized associated with the engineering and development of the cargo system, current	18.3	6.0
Net costs capitalized associated with the engineering and development of the cargo system, non-current	$ 111.2	$ 124.9