Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Operating Loss Carryforwards [Line Items]
Income taxes paid	$ 175.3	$ 269.6	$ 452.6
Unrecognized tax benefits that would impact effective tax rates if recognized	26.9	12.6
Unrecognized tax benefits, interest and penalties accrued	1.8	$ 0.9
Revaluation of net deferred tax liability	175.6
Provisional transition tax liability	9.8
Foreign withholding taxes	3.7
G & K Services
Operating Loss Carryforwards [Line Items]
Foreign withholding taxes	$ 0.7