Retirement Benefits and Postemployment Benefits (Schedule of estimated benefit payments) (Details) $ in Millions	May 28, 2017 USD ($)
Defined Benefit Plan Estimated Future Benefit Payments [Abstract]
Medicare Subsidy Receipts, Next Twelve Months	$ 4.3
Medicare Subsidy Receipts, Year Two	4.6
Medicare Subsidy Receipts, Year Three	4.2
Medicare Subsidy Receipts, Year Four	3.5
Medicare Subsidy Receipts, Year Five	3.6
Medicare Subsidy Receipts, Five Fiscal Years Thereafter	18.8
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Abstract]
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	290.2
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	298.6
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	307.7
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	316.4
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	325.7
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	1,767.8
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Abstract]
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	59.5
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	61.6
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	63.0
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	64.1
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	64.8
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	328.8
Postemployment Benefit Plans [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Abstract]
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	21.2
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	19.0
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	17.4
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	16.1
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	15.0
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	$ 61.5