Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019	May 31, 2020
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 37.7		$ 37.7		$ 35.9
Effective tax rate	13.30%	20.10%	10.50%	15.40%