Retirement Benefits and Postemployment Benefits (Schedule of asset allocations for benefit plans) (Details)	May 29, 2016	May 31, 2015
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 Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	30.50%	28.90%
Defined Benefit Pension Plans [Member] | International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	19.00%	18.40%
Defined Benefit Pension Plans [Member] | Private Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	8.30%	9.50%
Defined Benefit Pension Plans [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	28.60%	30.30%
Defined Benefit Pension Plans [Member] | Real asset investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	13.60%	12.90%
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 Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	37.20%	38.70%
Other Postretirement Benefit Plans [Member] | International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	23.40%	24.10%
Other Postretirement Benefit Plans [Member] | Private Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	3.90%	4.10%
Other Postretirement Benefit Plans [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	29.40%	26.30%
Other Postretirement Benefit Plans [Member] | Real asset investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	6.10%	6.80%