Other Expense, Net (Schedule of Other Expense, Net) (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2020	Aug. 31, 2019
Other Expense, Net [Abstract]
Interest income on corporate investments	$ 0.6	$ 4.5
Interest expense	(9.0)	(10.3)
Other	0.5	1.0
Other expense, net	$ (7.9)	$ (4.8)