Debt (Schedule of fee-paid committed and uncommitted credit lines) (Details) $ in Billions	9 Months Ended
	Feb. 28, 2021 USD ($)
Line Of Credit Facility [Line Items]
Facility Amount	$ 3.5
Borrowed Amount	0.2
Committed Credit Facilities [Member]
Line Of Credit Facility [Line Items]
Facility Amount	2.9
Borrowed Amount	$ 0.1
Minimum fixed charge coverage ratio	2.5
Line of Credit Expiring May 2022 [Member]
Line Of Credit Facility [Line Items]
Facility Amount	$ 2.7
Borrowed Amount	$ 0.0
Expiration date of credit facility	May 31, 2022
Line Of Credit Expiring September 2022 [Member]
Line Of Credit Facility [Line Items]
Facility Amount	$ 0.2
Borrowed Amount	$ 0.1
Expiration date of credit facility	Sep. 17, 2022
Uncommitted Credit Facilities [Member]
Line Of Credit Facility [Line Items]
Facility Amount	$ 0.6
Borrowed Amount	$ 0.1