Retirement Benefits and Postemployment Benefits (Schedule of asset allocations for benefit plans) (Details)	May 31, 2020	May 26, 2019
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	100.00%	100.00%
Defined Benefit Pension Plans [Member] | United States Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	19.70%	20.30%
Defined Benefit Pension Plans [Member] | International Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	11.00%	12.50%
Defined Benefit Pension Plans [Member] | Private Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	6.20%	8.10%
Defined Benefit Pension Plans [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	52.80%	46.70%
Defined Benefit Pension Plans [Member] | Real asset investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	10.30%	12.40%
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	100.00%	100.00%
Other Postretirement Benefit Plans [Member] | United States Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	18.10%	19.10%
Other Postretirement Benefit Plans [Member] | International Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	9.80%	11.20%
Other Postretirement Benefit Plans [Member] | Private Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	4.40%	4.90%
Other Postretirement Benefit Plans [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	64.80%	61.30%
Other Postretirement Benefit Plans [Member] | Real asset investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	2.90%	3.50%