Retirement Benefits and Postemployment Benefits (Schedule of components of net periodic benefit expense) (Details) - USD ($) $ in Millions	12 Months Ended
	May 28, 2017	May 29, 2016	May 31, 2015
Defined Benefit Pension Plans [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 119.7	$ 134.6	$ 137.0
Interest cost	216.5	267.8	249.2
Expected return on plan assets	(486.7)	(496.9)	(476.4)
Amortization of losses	190.2	189.8	141.7
Amortization of prior service costs (credits)	2.5	4.7	7.4
Other adjustments	3.1	5.0	15.1
Settlement or curtailment losses	3.8	13.1	18.0
Net (income) expense	49.1	118.1	92.0
Other Postretirement Benefit Plans [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	12.5	19.0	22.4
Interest cost	32.2	44.1	46.9
Expected return on plan assets	(48.5)	(46.2)	(40.2)
Amortization of losses	2.5	6.6	4.9
Amortization of prior service costs (credits)	(5.4)	(5.4)	(1.6)
Other adjustments	1.3	2.3	3.3
Settlement or curtailment losses	(0.9)	(1.0)	1.3
Net (income) expense	(6.3)	19.4	37.0
Postemployment Benefit Plans [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	8.8	7.6	7.5
Interest cost	2.6	3.9	4.3
Expected return on plan assets	0.0	0.0	0.0
Amortization of losses	1.7	0.7	0.7
Amortization of prior service costs (credits)	0.6	2.5	2.4
Other adjustments	1.3	10.7	9.5
Settlement or curtailment losses	(1.4)	0.0	0.0
Net (income) expense	$ 13.6	$ 25.4	$ 24.4