Retirement Benefits and Postemployment Benefits (Schedule of components of net periodic benefit expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 26, 2013	May 27, 2012	May 29, 2011
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Net Periodic Benefit Cost [Abstract]
Service cost	$ 124.4	$ 114.3	$ 101.4
Interest cost	237.3	237.9	230.9
Expected return on plan assets	(428.0)	(440.3)	(408.5)
Amortization of losses	136.0	108.1	81.4
Amortization of prior service costs (credits)	6.2	8.6	9.0
OtherAdjustments	0	0	0
Net (income) expense	75.9	28.6	14.2
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Net Periodic Benefit Cost [Abstract]
Service cost	21.6	18.0	18.7
Interest cost	52.1	55.6	60.1
Expected return on plan assets	(32.1)	(35.5)	(33.2)
Amortization of losses	17.1	14.5	14.4
Amortization of prior service costs (credits)	(3.4)	(3.4)	(0.6)
OtherAdjustments	0	0	0
Net (income) expense	55.3	49.2	59.4
Postemployment Benefit Plans [Member]
Defined Benefit Plan Net Periodic Benefit Cost [Abstract]
Service cost	7.8	7.5	8.0
Interest cost	4.4	4.8	5.1
Expected return on plan assets	0	0	0
Amortization of losses	2.1	1.7	2.1
Amortization of prior service costs (credits)	1.9	2.1	2.4
OtherAdjustments	11.4	12.0	4.2
Net (income) expense	$ 27.6	$ 28.1	$ 21.8