Retirement Benefits and Postemployment Benefits (Schedule of level 3 investments of benefit plan assets) (Details) (USD $) In Millions, unless otherwise specified												12 Months Ended																					12 Months Ended
	May 26, 2013 Defined Benefit Pension Plans [Member]	May 27, 2012 Defined Benefit Pension Plans [Member]	May 29, 2011 Defined Benefit Pension Plans [Member]	May 26, 2013 Defined Benefit Pension Plans [Member] Equity [Member]	May 27, 2012 Defined Benefit Pension Plans [Member] Equity [Member]	May 26, 2013 Defined Benefit Pension Plans [Member] Fixed income [Member]	May 27, 2012 Defined Benefit Pension Plans [Member] Fixed income [Member]	May 26, 2013 Defined Benefit Pension Plans [Member] Real asset investments [Member]	May 27, 2012 Defined Benefit Pension Plans [Member] Real asset investments [Member]	May 26, 2013 Defined Benefit Pension Plans [Member] Other Investments [Member]	May 27, 2012 Defined Benefit Pension Plans [Member] Other Investments [Member]	May 26, 2013 Defined Benefit Pension Plans [Member] Level 3 [Member]	May 27, 2012 Defined Benefit Pension Plans [Member] Level 3 [Member]	May 26, 2013 Defined Benefit Pension Plans [Member] Level 3 [Member] Equity [Member]	May 27, 2012 Defined Benefit Pension Plans [Member] Level 3 [Member] Equity [Member]	May 26, 2013 Defined Benefit Pension Plans [Member] Level 3 [Member] Fixed income [Member]	May 27, 2012 Defined Benefit Pension Plans [Member] Level 3 [Member] Fixed income [Member]	May 26, 2013 Defined Benefit Pension Plans [Member] Level 3 [Member] Real asset investments [Member]	May 27, 2012 Defined Benefit Pension Plans [Member] Level 3 [Member] Real asset investments [Member]	May 26, 2013 Defined Benefit Pension Plans [Member] Level 3 [Member] Other Investments [Member]	May 27, 2012 Defined Benefit Pension Plans [Member] Level 3 [Member] Other Investments [Member]	May 26, 2013 Other Postretirement Benefit Plans [Member]	May 27, 2012 Other Postretirement Benefit Plans [Member]	May 29, 2011 Other Postretirement Benefit Plans [Member]	May 26, 2013 Other Postretirement Benefit Plans [Member] Equity [Member]	May 27, 2012 Other Postretirement Benefit Plans [Member] Equity [Member]	May 26, 2013 Other Postretirement Benefit Plans [Member] Fixed income [Member]	May 27, 2012 Other Postretirement Benefit Plans [Member] Fixed income [Member]	May 26, 2013 Other Postretirement Benefit Plans [Member] Real asset investments [Member]	May 27, 2012 Other Postretirement Benefit Plans [Member] Real asset investments [Member]	May 26, 2013 Other Postretirement Benefit Plans [Member] Other Investments [Member]	May 27, 2012 Other Postretirement Benefit Plans [Member] Other Investments [Member]	May 26, 2013 Other Postretirement Benefit Plans [Member] Level 3 [Member]	May 27, 2012 Other Postretirement Benefit Plans [Member] Level 3 [Member]	May 26, 2013 Other Postretirement Benefit Plans [Member] Level 3 [Member] Equity [Member]	May 27, 2012 Other Postretirement Benefit Plans [Member] Level 3 [Member] Equity [Member]	May 26, 2013 Other Postretirement Benefit Plans [Member] Level 3 [Member] Fixed income [Member]	May 27, 2012 Other Postretirement Benefit Plans [Member] Level 3 [Member] Fixed income [Member]	May 26, 2013 Other Postretirement Benefit Plans [Member] Level 3 [Member] Real asset investments [Member]	May 27, 2012 Other Postretirement Benefit Plans [Member] Level 3 [Member] Real asset investments [Member]	May 26, 2013 Other Postretirement Benefit Plans [Member] Level 3 [Member] Other Investments [Member]	May 27, 2012 Other Postretirement Benefit Plans [Member] Level 3 [Member] Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year	$ 5,066.1	$ 4,353.9	$ 4,264.0	$ 2,827.0	$ 2,412.2	$ 1,277.6	$ 1,153.3	$ 730.6	$ 585.1	$ 61.2	$ 49.9	$ 936.9	$ 925.9	$ 575.4	$ 568.5	$ 0	$ 0.2	$ 361.2	$ 356.9	$ 0.3	$ 0.3	$ 436.9	$ 358.8	$ 353.8	$ 205.3	$ 170.0	$ 67.5	$ 54.8	$ 23.4	$ 18.4	$ 130.9	$ 104.9	$ 30.4	$ 40.1	$ 22.0	$ 26.3	$ 0	$ 0.2	$ 8.4	$ 13.6	$ 0	$ 0
Transfers In/(Out)												(0.1)	(50.1)	(0.1)	(1.2)	0	0	0	(48.9)	0	0												0	(4.0)	0	0	0	0	0	(4.0)
Purchases, Sales Issuances, and Settlements (Net)												(12.7)	4.2	(61.0)	(28.4)	0	(0.2)	48.3	32.8	0	0												2.5	(5.2)	(2.3)	(4.1)	0	0	4.8	(1.1)
Actual return on plan assets still held												65.9	56.9	45.0	36.5	0	0	20.9	20.4	0	0												1.8	(0.5)	0.5	(0.2)	0	(0.2)	1.3	(0.1)
Fair value at end of year	$ 5,066.1	$ 4,353.9	$ 4,264.0	$ 2,827.0	$ 2,412.2	$ 1,277.6	$ 1,153.3	$ 730.6	$ 585.1	$ 61.2	$ 49.9	$ 990.0	$ 936.9	$ 559.3	$ 575.4	$ 0	$ 0	$ 430.4	$ 361.2	$ 0.3	$ 0.3	$ 436.9	$ 358.8	$ 353.8	$ 205.3	$ 170.0	$ 67.5	$ 54.8	$ 23.4	$ 18.4	$ 130.9	$ 104.9	$ 34.7	$ 30.4	$ 20.2	$ 22.0	$ 0	$ 0	$ 14.5	$ 8.4	$ 0	$ 0