Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Aug. 31, 2014	Aug. 31, 2013
Accumulated Other Comprehensive Loss
Balance at the beginning of the period	$ (29.3)	$ (42.5)
Other comprehensive income (loss) before reclassifications	(8.7)	3.7
Amounts reclassified from AOCL	0.1	0.2
Other comprehensive (loss) income, net of tax	(8.6)	3.9
Balance at the end of the period	(37.9)	(38.6)
Currency Translation Adjustments
Accumulated Other Comprehensive Loss
Balance at the beginning of the period	8.7	(5.4)
Other comprehensive income (loss) before reclassifications	(9.0)	2.8
Other comprehensive (loss) income, net of tax	(9.0)	2.8
Balance at the end of the period	(0.3)	(2.6)
Pensions Plans
Accumulated Other Comprehensive Loss
Balance at the beginning of the period	(35.4)	(33.8)
Amounts reclassified from AOCL	0.1	0.2
Other comprehensive (loss) income, net of tax	0.1	0.2
Balance at the end of the period	(35.3)	(33.6)
Derivative Instruments
Accumulated Other Comprehensive Loss
Balance at the beginning of the period	(2.6)	(3.3)
Other comprehensive income (loss) before reclassifications	0.3	0.9
Other comprehensive (loss) income, net of tax	0.3	0.9
Balance at the end of the period	$ (2.3)	$ (2.4)