Income Taxes (Reconciliation of Gross Unrecognized Tax Benefits, Not Including Interest or Other Potential Offsetting Effects) (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2019
Income Taxes [Abstract]
Balance as of beginning of fiscal year	$ 26.2	$ 22.1	$ 14.9
Additions for tax positions of the current year	5.5	4.1	3.8
Additions for tax positions of prior years	9.2	1.2	5.2
Reductions for tax positions of prior years		(0.6)
Settlements with tax authorities	(15.2)		(1.2)
Expiration of the statute of limitations	(3.3)	(0.6)	(0.6)
Balance as of end of fiscal year	$ 22.4	$ 26.2	$ 22.1