Business Segment Information (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	May 31, 2014	Feb. 28, 2014	Nov. 30, 2013	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2014	May 31, 2013	May 31, 2012
Business Segment Information
Sales	$ 505.4	$ 474.4	$ 540.7	$ 514.5	$ 553.8	$ 520.2	$ 512.8	$ 550.5	$ 2,035.0	$ 2,137.3	$ 2,065.0
U.S. Department of Defense, other U.S. government agencies and their contractors
Business Segment Information
Sales									694.9	763.2	888.5
Percentage of total sales									34.10%	35.70%	43.00%
Aviation Services
Business Segment Information
Sales									1,560.0	1,614.4	1,536.0
Aviation Services | U.S. Department of Defense, other U.S. government agencies and their contractors
Business Segment Information
Sales									521.3	548.2	534.9
Technology Products
Business Segment Information
Sales									475.0	522.9	529.0
Technology Products | U.S. Department of Defense, other U.S. government agencies and their contractors
Business Segment Information
Sales									$ 173.6	$ 215.0	$ 353.6