Business Segment Information - Sales by Product and Services (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2018	May 31, 2017	May 31, 2016
Net sales	$ 473.5	$ 456.3	$ 420.6	$ 397.9	$ 450.5	$ 407.2	$ 371.3	$ 361.8	$ 1,748.3	$ 1,590.8	$ 1,525.4
Aviation supply chain
Net sales									1,066.0	998.7	903.2
Maintenance, repair and overhaul services
Net sales									552.9	486.7	521.8
Mobility products
Net sales									112.5	$ 105.4	$ 100.4
Airlift
Net sales									$ 16.9