Retirement Benefits and Postemployment Benefits (Schedule of plans with accumulated benefit obiligations in excess of plan assets) (Details) - USD ($) $ in Millions	May 27, 2018	May 28, 2017
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets [Abstract]
Projected benefit obligation	$ 551.6	$ 610.1
Accumulated benefit obligation	498.8	542.3
Plan assets at fair value	10.2	51.9
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets [Abstract]
Projected benefit obligation	5.4	5.5
Accumulated benefit obligation	868.3	947.9
Plan assets at fair value	726.1	694.8
Postemployment Benefit Plans [Member]
Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets [Abstract]
Projected benefit obligation	0.0	4.4
Accumulated benefit obligation	122.0	130.1
Plan assets at fair value	$ 0.0	$ 0.0