Pension and Postretirement Benefits (Details 6) (USD $) In Millions, unless otherwise specified	May 27, 2012	May 29, 2011
Fair value of Plan assets
Total Assets	$ 2,766.6	$ 2,543.9
Level 1 [Member]
Fair value of Plan assets
Total Assets	1,354.7	1,427.4
Level 2 [Member]
Fair value of Plan assets
Total Assets	883.8	644.2
Level 3 [Member]
Fair value of Plan assets
Total Assets	528.1	472.3
Cash and cash equivalents [Member]
Fair value of Plan assets
Total Assets	321.6	124.2
Cash and cash equivalents [Member] | Level 1 [Member]
Fair value of Plan assets
Total Assets	1.8	2.7
Cash and cash equivalents [Member] | Level 2 [Member]
Fair value of Plan assets
Total Assets	319.8	121.5
U.S. equity securities [Member]
Fair value of Plan assets
Total Assets	623.5	633.4
U.S. equity securities [Member] | Level 1 [Member]
Fair value of Plan assets
Total Assets	616.2	625.7
U.S. equity securities [Member] | Level 2 [Member]
Fair value of Plan assets
Total Assets	7.3	7.7
International equity securities [Member]
Fair value of Plan assets
Total Assets	521.8	604.6
International equity securities [Member] | Level 1 [Member]
Fair value of Plan assets
Total Assets	395.1	473.1
International equity securities [Member] | Level 2 [Member]
Fair value of Plan assets
Total Assets	126.7	131.5
Government bonds [Member]
Fair value of Plan assets
Total Assets	260.5	208.5
Government bonds [Member] | Level 1 [Member]
Fair value of Plan assets
Total Assets	99.9	53.4
Government bonds [Member] | Level 2 [Member]
Fair value of Plan assets
Total Assets	160.6	155.1
Corporate bonds [Member]
Fair value of Plan assets
Total Assets	208.6	273.0
Corporate bonds [Member] | Level 1 [Member]
Fair value of Plan assets
Total Assets	9.5	103.5
Corporate bonds [Member] | Level 2 [Member]
Fair value of Plan assets
Total Assets	199.1	169.5
Mortgage-backed bonds [Member]
Fair value of Plan assets
Total Assets	152.7	90.4
Mortgage-backed bonds [Member] | Level 1 [Member]
Fair value of Plan assets
Total Assets	82.4	31.5
Mortgage-backed bonds [Member] | Level 2 [Member]
Fair value of Plan assets
Total Assets	70.3	58.9
Real estate funds [Member]
Fair value of Plan assets
Total Assets	88.9	78.1
Real estate funds [Member] | Level 1 [Member]
Fair value of Plan assets
Total Assets	5.7	7.8
Real estate funds [Member] | Level 3 [Member]
Fair value of Plan assets
Total Assets	83.2	70.3
Multi-strategy hedge funds [Member]
Fair value of Plan assets
Total Assets	379.1	346.0
Multi-strategy hedge funds [Member] | Level 3 [Member]
Fair value of Plan assets
Total Assets	379.1	346.0
Private equity [Member]
Fair value of Plan assets
Total Assets	64.2	56.0
Private equity [Member] | Level 3 [Member]
Fair value of Plan assets
Total Assets	64.2	56.0
Master limited partnerships [Member]
Fair value of Plan assets
Total Assets	137.5	125.2
Master limited partnerships [Member] | Level 1 [Member]
Fair value of Plan assets
Total Assets	137.5	125.2
Private energy funds [Member]
Fair value of Plan assets
Total Assets	1.6
Private energy funds [Member] | Level 3 [Member]
Fair value of Plan assets
Total Assets	1.6
Net receivables for unsettled transactions [Member]
Fair value of Plan assets
Total Assets	6.6	4.5
Net receivables for unsettled transactions [Member] | Level 1 [Member]
Fair value of Plan assets
Total Assets	$ 6.6	$ 4.5