Financial Instruments, Risk Management Activities, and Fair Values (Schedule of fair value measurement inputs) (Details) (USD $) In Millions, unless otherwise specified	May 26, 2013	May 27, 2012
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	$ 140.5	$ 57.6
Total Assets Fair Value Disclosure	194.1	99.2
Other Liabilities Fair Value Disclosure	0	0
Total Liabilities Fair Value Disclosure	(36.2)	(55.7)
Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	26.0	17.2
Derivative Liability Fair Value	(1.6)	(18.8)
Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	27.6	24.4
Derivative Liability Fair Value	(34.6)	(36.9)
Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	6.4	5.3
Total Assets Fair Value Disclosure	16.7	13.3
Other Liabilities Fair Value Disclosure	0	0
Total Liabilities Fair Value Disclosure	0	0
Level 1 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Level 1 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	10.3	8.0
Derivative Liability Fair Value	0	0
Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	134.1	52.3
Total Assets Fair Value Disclosure	177.4	85.9
Other Liabilities Fair Value Disclosure	0	0
Total Liabilities Fair Value Disclosure	(36.2)	(55.7)
Level 2 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	26.0	17.2
Derivative Liability Fair Value	(1.6)	(18.8)
Level 2 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	17.3	16.4
Derivative Liability Fair Value	(34.6)	(36.9)
Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	0	0
Total Assets Fair Value Disclosure	0	0
Other Liabilities Fair Value Disclosure	0	0
Total Liabilities Fair Value Disclosure	0	0
Level 3 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Level 3 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	10.3	5.7
Derivative Liability Fair Value	0	0
Interest Rate Contract [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value		0.5
Derivative Liability Fair Value		0
Interest Rate Contract [Member] | Level 1 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Interest Rate Contract [Member] | Level 1 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value		0
Derivative Liability Fair Value		0
Interest Rate Contract [Member] | Level 2 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	10.3	5.7
Derivative Liability Fair Value	0	0
Interest Rate Contract [Member] | Level 2 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value		0.5
Derivative Liability Fair Value		0
Interest Rate Contract [Member] | Level 3 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Interest Rate Contract [Member] | Level 3 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value		0
Derivative Liability Fair Value		0
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	15.7	11.5
Derivative Liability Fair Value	(1.6)	(18.8)
Foreign Exchange Contract [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	6.7	6.6
Derivative Liability Fair Value	(0.1)	(1.1)
Foreign Exchange Contract [Member] | Level 1 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Foreign Exchange Contract [Member] | Level 1 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Foreign Exchange Contract [Member] | Level 2 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	15.7	11.5
Derivative Liability Fair Value	(1.6)	(18.8)
Foreign Exchange Contract [Member] | Level 2 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	6.7	6.6
Derivative Liability Fair Value	(0.1)	(1.1)
Foreign Exchange Contract [Member] | Level 3 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Foreign Exchange Contract [Member] | Level 3 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Equity Contract [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	(0.2)	(0.1)
Equity Contract [Member] | Level 1 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Equity Contract [Member] | Level 2 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	(0.2)	(0.1)
Equity Contract [Member] | Level 3 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Commodity Contract [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	13.4	9.0
Derivative Liability Fair Value	(3.9)	(15.1)
Commodity Contract [Member] | Level 1 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	10.3	8.0
Derivative Liability Fair Value	0	0
Commodity Contract [Member] | Level 2 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	3.1	1.0
Derivative Liability Fair Value	(3.9)	(15.1)
Commodity Contract [Member] | Level 3 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Grain Contracts [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	7.5	8.3
Derivative Liability Fair Value	(30.4)	(20.6)
Grain Contracts [Member] | Level 1 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Grain Contracts [Member] | Level 2 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	7.5	8.3
Derivative Liability Fair Value	(30.4)	(20.6)
Grain Contracts [Member] | Level 3 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	0	0
Derivative Liability Fair Value	0	0
Marketable Investments [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	140.5	57.6
Other Liabilities Fair Value Disclosure	0	0
Marketable Investments [Member] | Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	6.4	5.3
Other Liabilities Fair Value Disclosure	0	0
Marketable Investments [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	134.1	52.3
Other Liabilities Fair Value Disclosure	0	0
Marketable Investments [Member] | Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	0	0
Other Liabilities Fair Value Disclosure	$ 0	$ 0