Summary of Significant Accounting Policies (Details 5) $ in Millions	12 Months Ended
	May. 31, 2015 USD ($) aircraft	May. 31, 2014 USD ($) aircraft
Inventories
Raw materials and parts	$ 43.1	$ 114.1
Work-in-process	18.1	57.5
Aircraft and engine parts, components and finished goods	337.0	297.3
Aircraft held for sale and related support parts	57.8	26.4
Total inventories	$ 456.0	$ 495.3
Number of Aircrafts Held for Sale | aircraft	11	9
Inventory impairment charge	$ 8.9
Proceeds from sale-leaseback advance	$ 40.3
Fixed-wing aircraft
Inventories
Number of Aircrafts Held for Sale | aircraft	5	5
Rotary-wing aircraft
Inventories
Number of Aircrafts Held for Sale | aircraft	6	4
Number of aircrafts under sale leaseback transaction | aircraft	2