Additional Financial Information (Supplemental Balance Sheet Information) (Details) - USD ($) $ in Millions	Feb. 28, 2021	May 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Operating lease right-of-use assets	$ 3,842.8	$ 3,969.2
Finance lease right-of-use assets	346.8	235.2
Total lease assets, net	4,189.6	4,204.4
Operating lease liabilities - current	173.1	160.6
Finance lease liabilities - current	5.7	5.7
Operating lease liabilities - non-current	4,156.3	4,276.3
Finance lease liabilities - non-current	490.1	368.4
Total lease liabilities	$ 4,825.2	$ 4,811.0
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtCurrent
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term debt
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term debt