Accumulated Other Comprehensive Income (Loss) - Schedule of AOCI Activity (Details) $ in Millions	3 Months Ended
	Aug. 31, 2015 USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (77.0)
Less: amount reclassified from Accumulated other comprehensive income (loss)	(6.6)
Other comprehensive income (loss)	(6.6)
Ending balance	(83.6)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(31.9)
Less: amount reclassified from Accumulated other comprehensive income (loss)	(7.3)
Other comprehensive income (loss)	(7.3)
Ending balance	(39.2)
Retirement benefit plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(45.1)
Less: amount reclassified from Accumulated other comprehensive income (loss)	0.7
Other comprehensive income (loss)	0.7
Ending balance	$ (44.4)