Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2017	May 31, 2016	May 31, 2015
Accumulated Other Comprehensive Loss
Balance at beginning of the period	$ (44.4)	$ (40.4)	$ (29.3)
Other comprehensive income (loss) before reclassifications from AOCL	2.9	(5.6)	(64.2)
Amounts reclassified from AOCL	1.6	1.6	3.4
Total other comprehensive income (loss), net of tax	4.5	(4.0)	(11.1)
Balance at end of the period	(39.9)	(44.4)	(40.4)
Currency Translation Adjustments
Accumulated Other Comprehensive Loss
Balance at beginning of the period	(1.1)	0.9	8.7
Reclassification within AOCL		(2.0)
Other comprehensive income (loss) before reclassifications from AOCL	(0.6)		(56.9)
Total other comprehensive income (loss), net of tax	(0.6)		(7.8)
Balance at end of the period	(1.7)	(1.1)	0.9
Pensions Plans
Accumulated Other Comprehensive Loss
Balance at beginning of the period	(43.3)	(41.3)	(35.4)
Reclassification within AOCL		2.0
Other comprehensive income (loss) before reclassifications from AOCL	3.5	(5.6)	(7.9)
Amounts reclassified from AOCL	1.6	1.6	1.4
Total other comprehensive income (loss), net of tax	5.1	(4.0)	(5.9)
Balance at end of the period	$ (38.2)	$ (43.3)	(41.3)
Derivative Instruments
Accumulated Other Comprehensive Loss
Balance at beginning of the period			(2.6)
Other comprehensive income (loss) before reclassifications from AOCL			0.6
Amounts reclassified from AOCL			2.0
Total other comprehensive income (loss), net of tax			2.6
Telair Cargo Group
Accumulated Other Comprehensive Loss
Gain recognized on sale of business			49.7
Telair Cargo Group | Currency Translation Adjustments
Accumulated Other Comprehensive Loss
Gain recognized on sale of business			49.1
Telair Cargo Group | Pensions Plans
Accumulated Other Comprehensive Loss
Gain recognized on sale of business			$ 0.6