Business Segment Information (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2013	May 31, 2012	May 31, 2011
Business Segment Information
Sales	$ 553.8	$ 520.2	$ 512.8	$ 550.5	$ 563.3	$ 534.2	$ 482.0	$ 485.5	$ 2,137.3	$ 2,065.0	$ 1,805.1
U.S. Department of Defense, other U.S. government agencies and their contractors
Business Segment Information
Sales									763.2	888.5	893.1
Percentage of total sales									35.70%	43.00%	49.50%
Aviation Services
Business Segment Information
Sales									1,614.4	1,536.0	1,398.2
Aviation Services | U.S. Department of Defense, other U.S. government agencies and their contractors
Business Segment Information
Sales									548.2	534.9	540.3
Technology Products
Business Segment Information
Sales									522.9	529.0	406.9
Technology Products | U.S. Department of Defense, other U.S. government agencies and their contractors
Business Segment Information
Sales									$ 215.0	$ 353.6	$ 352.8