Business Segment Information (Details) (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 item	May 31, 2013	May 31, 2012
Business Segment Information
Number of business segments									2
Business Segment Information
Net 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
Gross Profit	85.8	78.7	91.0	84.7	60.3	76.2	87.4	90.3	340.2	314.2	318.6
Total assets	2,199.5				2,136.9				2,199.5	2,136.9	2,195.7
Capital expenditures									26.5	37.6	91.2
Depreciation and amortization, including depreciation and amortization of stock-based compensation									89.1	90.8	84.5
Aviation Services
Business Segment Information
Net sales									1,560.0	1,614.4	1,536.0
Gross Profit									258.9	227.5	237.3
Total assets	1,266.9				1,262.8				1,266.9	1,262.8	1,360.1
Capital expenditures									17.8	28.8	77.5
Depreciation and amortization, including depreciation and amortization of stock-based compensation									57.4	59.5	56.0
Technology Products
Business Segment Information
Net sales									475.0	522.9	529.0
Gross Profit									81.3	86.7	81.3
Total assets	751.5				716.6				751.5	716.6	675.4
Capital expenditures									6.4	7.7	12.3
Depreciation and amortization, including depreciation and amortization of stock-based compensation									21.1	19.6	15.7
Corporate
Business Segment Information
Total assets	181.1				157.5				181.1	157.5	160.2
Capital expenditures									2.3	1.1	1.4
Depreciation and amortization, including depreciation and amortization of stock-based compensation									$ 10.6	$ 11.7	$ 12.8