Summary of Significant Accounting Policies - Restructuring and Other Exit Costs, Supplemental Information on Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2019
Supplemental Information on Cash Flows
Interest paid	$ 4.3	$ 8.6	$ 8.8
Income taxes paid	8.2	14.3	7.0
Income tax refunds and interest received	8.3	7.0	$ 6.4
Cost of sales and services and Selling, general and administrative
Restructuring and Impairment Costs
Severance and furlough-related costs	$ 9.0	$ 7.1