Financial Instruments, Risk Management Activities, and Fair Values (Schedule of fair value measurement inputs) (Details) (USD $) In Millions, unless otherwise specified	Aug. 25, 2013	May 26, 2013
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	$ 83.4	$ 65.8
Other Assets Fair Value Disclosure	129.9	140.5
Total Assets Fair Value Disclosure	224.7	194.1
Derivative Liability Fair Value	31.6	25.2
Other Liabilities Fair Value Disclosure	0	0
Total Liabilities Fair Value Disclosure	(60.9)	(36.2)
Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	39.5	26.0
Derivative Liability Fair Value	(4.4)	(1.6)
Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	55.3	27.6
Derivative Liability Fair Value	(56.5)	(34.6)
Fair Value Inputs Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	6.8	6.4
Total Assets Fair Value Disclosure	20.4	16.7
Other Liabilities Fair Value Disclosure	0	0
Total Liabilities Fair Value Disclosure	0	0
Fair Value Inputs 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
Fair Value Inputs Level 1 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	13.6	10.3
Derivative Liability Fair Value	0	0
Fair Value Inputs Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	123.1	134.1
Total Assets Fair Value Disclosure	204.3	177.4
Other Liabilities Fair Value Disclosure		0
Total Liabilities Fair Value Disclosure	(60.9)	(36.2)
Fair Value Inputs Level 2 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	39.5	26.0
Derivative Liability Fair Value	(4.4)	(1.6)
Fair Value Inputs Level 2 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	41.7	17.3
Derivative Liability Fair Value	(56.5)	(34.6)
Fair Value Inputs 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
Fair Value Inputs 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
Fair Value Inputs 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 Fair Value [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	23.7	10.3
Derivative Liability Fair Value	(0.8)	0
Interest Rate Contract Fair Value [Member] | Fair Value Inputs 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 Fair Value [Member] | Fair Value Inputs Level 2 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	23.7	10.3
Derivative Liability Fair Value	(0.8)	0
Interest Rate Contract Fair Value [Member] | Fair Value Inputs 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 Fair Value [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	15.8	15.7
Derivative Liability Fair Value	(3.6)	(1.6)
Foreign Exchange Contract Fair Value [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	1.5	6.7
Derivative Liability Fair Value	(2.9)	(0.1)
Foreign Exchange Contract Fair Value [Member] | Fair Value Inputs 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 Fair Value [Member] | Fair Value Inputs 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 Fair Value [Member] | Fair Value Inputs Level 2 [Member] | Designated as Hedging Instrument [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	15.8	15.7
Derivative Liability Fair Value	(3.6)	(1.6)
Foreign Exchange Contract Fair Value [Member] | Fair Value Inputs Level 2 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	1.5	6.7
Derivative Liability Fair Value	(2.9)	(0.1)
Foreign Exchange Contract Fair Value [Member] | Fair Value Inputs 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 Fair Value [Member] | Fair Value Inputs 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)	(0.2)
Equity Contract [Member] | Fair Value Inputs 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] | Fair Value Inputs 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)	(0.2)
Equity Contract [Member] | Fair Value Inputs 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 Fair Value [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	42.4	13.4
Derivative Liability Fair Value	(24.2)	(3.9)
Commodity Contract Fair Value [Member] | Fair Value Inputs Level 1 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	13.6	10.3
Derivative Liability Fair Value	0	0
Commodity Contract Fair Value [Member] | Fair Value Inputs Level 2 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	28.8	3.1
Derivative Liability Fair Value	(24.2)	(3.9)
Commodity Contract Fair Value [Member] | Fair Value Inputs 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	11.4	7.5
Derivative Liability Fair Value	(29.2)	(30.4)
Grain Contracts [Member] | Fair Value Inputs 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] | Fair Value Inputs Level 2 [Member] | Not Designated as Hedging [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Fair Value	11.4	7.5
Derivative Liability Fair Value	(29.2)	(30.4)
Grain Contracts [Member] | Fair Value Inputs 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	129.9	140.5
Other Liabilities Fair Value Disclosure	0	0
Marketable Investments [Member] | Fair Value Inputs Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	6.8	6.4
Other Liabilities Fair Value Disclosure	0	0
Marketable Investments [Member] | Fair Value Inputs Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other Assets Fair Value Disclosure	123.1	134.1
Other Liabilities Fair Value Disclosure		0
Marketable Investments [Member] | Fair Value Inputs 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