Retirement Benefits and Postemployment Benefits (Schedule of asset allocations for benefit plans) (Details)	May 28, 2017	May 29, 2016
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	28.50%	30.50%
Defined Benefit Pension Plans [Member] | International Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	17.90%	19.00%
Defined Benefit Pension Plans [Member] | Private Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	7.80%	8.30%
Defined Benefit Pension Plans [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	31.70%	28.60%
Defined Benefit Pension Plans [Member] | Real assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	14.10%	13.60%
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	31.90%	37.20%
Other Postretirement Benefit Plans [Member] | International Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	17.80%	23.40%
Other Postretirement Benefit Plans [Member] | Private Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	3.60%	3.90%
Other Postretirement Benefit Plans [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	40.00%	29.40%
Other Postretirement Benefit Plans [Member] | Real assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Weighted-Average Asset Allocations	6.70%	6.10%