Retirement Benefits and Postemployment Benefits (Schedule of summarized financial information about benefit plans) (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 26, 2019	May 27, 2018
Defined Benefit Pension Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets Roll Forward [Abstract]
Fair value at beginning of year	$ 6,291.6	$ 6,177.4
Actual return on assets	983.7	391.9
Employer contributions	32.9	30.4
Plan participant contributions	6.7	3.9
Benefits payments	(317.2)	(305.2)
Foreign currency	(4.5)	(6.8)
Fair value at end of year	6,993.2	6,291.6	$ 6,177.4
Defined Benefit Plan, Change in Projected Benefit Obligation Roll Forward [Abstract]
Benefit obligation at beginning of year	6,750.7	6,416.0
Service cost	92.7	94.6	102.9
Interest cost	230.5	248.0	217.9
Plan amendment	1.2	0.0
Curtailment/other	(1.2)	(0.7)
Plan participant contributions	6.7	3.9
Medicare Part D reimbursements	0.0	0.0
Actuarial loss (gain)	881.8	301.8
Benefits payments	(317.7)	(305.8)
Foreign currency	(4.5)	(7.1)
Projected benefit obligation at end of year	7,640.2	6,750.7	6,416.0
Plan assets less than benefit obligation as of fiscal year end	(647.0)	(459.1)
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets Roll Forward [Abstract]
Fair value at beginning of year	753.8	726.1
Actual return on assets	65.0	41.3
Employer contributions	0.1	0.1
Plan participant contributions	13.8	15.0
Benefits payments	(39.2)	(28.7)
Foreign currency	0.0	0.0
Fair value at end of year	793.5	753.8	726.1
Defined Benefit Plan, Change in Projected Benefit Obligation Roll Forward [Abstract]
Benefit obligation at beginning of year	824.1	871.8
Service cost	9.4	9.9	11.6
Interest cost	27.1	33.1	30.1
Plan amendment	0.0	0.0
Curtailment/other	0.0	0.0
Plan participant contributions	13.8	15.0
Medicare Part D reimbursements	2.7	2.5
Actuarial loss (gain)	(38.3)	(45.4)
Benefits payments	(63.5)	(62.2)
Foreign currency	(1.6)	(0.6)
Projected benefit obligation at end of year	773.7	824.1	871.8
Plan assets less than benefit obligation as of fiscal year end	19.8	(70.3)
Postemployment Benefit Plans [Member]
Defined Benefit Plan, Change in Projected Benefit Obligation Roll Forward [Abstract]
Benefit obligation at beginning of year	128.0	126.7
Service cost	8.3	7.6	8.6
Interest cost	2.6	3.0	2.3
Plan amendment	0.0	1.7
Curtailment/other	0.0	0.0
Plan participant contributions	0.0	0.0
Medicare Part D reimbursements	0.0	0.0
Actuarial loss (gain)	17.7	2.6
Benefits payments	(6.2)	(13.2)
Foreign currency	(0.1)	(0.4)
Projected benefit obligation at end of year	150.3	128.0	$ 126.7
Plan assets less than benefit obligation as of fiscal year end	$ (150.3)	$ (128.0)