Financial Instruments, Risk Management Activities, and Fair Values (Schedule of offsetting assets and liabilities) (Details) (USD $) In Millions, unless otherwise specified	Nov. 23, 2014	May 25, 2014
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	$ 15.3	$ 30.3
Gross Liabilities Offset in the Balance Sheet	0	0
Net Amounts of Assets	15.3	30.3
Financial Instruments, Gross Amounts Not Offset in the Balance Sheet	(8.9)	(11.4)
Cash Collateral Received, Gross Amounts Not Offset in the Balance Sheet	0	0
Net Amount	6.4	18.9
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(36.9)	(23.1)
Gross Assets Offset in the Balance Sheet	0	0
Net Amounts of Liabilities	(36.9)	(23.1)
Financial Instruments, Gross Amounts Not Offset in the Balance Sheet	8.9	11.4
Cash Collateral Received, Gross Amounts Not Offset in the Balance Sheet	0	0
Net Amount	(28.0)	(11.7)
Commodity Contracts [Member]
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	0.7	19.1
Gross Liabilities Offset in the Balance Sheet	0	0
Net Amounts of Assets	0.7	19.1
Financial Instruments, Gross Amounts Not Offset in the Balance Sheet	(0.3)	(3.4)
Cash Collateral Received, Gross Amounts Not Offset in the Balance Sheet	0	0
Net Amount	0.4	15.7
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(21.1)	(4.0)
Gross Assets Offset in the Balance Sheet	0	0
Net Amounts of Liabilities	(21.1)	(4.0)
Financial Instruments, Gross Amounts Not Offset in the Balance Sheet	0.3	3.4
Cash Collateral Received, Gross Amounts Not Offset in the Balance Sheet	0	0
Net Amount	(20.8)	(0.6)
Interest Rate Contracts [Member]
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	0.5	0.7
Gross Liabilities Offset in the Balance Sheet	0	0
Net Amounts of Assets	0.5	0.7
Financial Instruments, Gross Amounts Not Offset in the Balance Sheet	0	0
Cash Collateral Received, Gross Amounts Not Offset in the Balance Sheet	0	0
Net Amount	0.5	0.7
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(2.5)	0
Gross Assets Offset in the Balance Sheet	0	0
Net Amounts of Liabilities	(2.5)	0
Financial Instruments, Gross Amounts Not Offset in the Balance Sheet	0	0
Cash Collateral Received, Gross Amounts Not Offset in the Balance Sheet	0	0
Net Amount	(2.5)	0
Foreign Exchange Contracts [Member]
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	14.1	10.5
Gross Liabilities Offset in the Balance Sheet	0	0
Net Amounts of Assets	14.1	10.5
Financial Instruments, Gross Amounts Not Offset in the Balance Sheet	(8.6)	(8.0)
Cash Collateral Received, Gross Amounts Not Offset in the Balance Sheet	0	0
Net Amount	5.5	2.5
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(13.3)	(19.1)
Gross Assets Offset in the Balance Sheet	0	0
Net Amounts of Liabilities	(13.3)	(19.1)
Financial Instruments, Gross Amounts Not Offset in the Balance Sheet	8.6	8.0
Cash Collateral Received, Gross Amounts Not Offset in the Balance Sheet	0	0
Net Amount	$ (4.7)	$ (11.1)