Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018
Income Tax Disclosure [Abstract]
Income taxes paid	$ 160.3	$ 173.2	$ 175.3
Unrecognized tax benefits that would impact effective tax rates if recognized	35.9	37.3
Unrecognized tax benefits, interest and penalties accrued	$ 3.7	$ 2.8