Financial Instruments, Risk Management Activities, and Fair Values (Schedule of swap contract maturities) (Details) (USD $) In Millions, unless otherwise specified	May 26, 2013
Interest Rate Swap Pay Floating [Member]
Derivative [Line Items]
Year One	$ 300.0
Year Two	0
Year Three	250.0
Total	550.0
Treasury Lock [Member]
Derivative [Line Items]
Year One	250.0
Year Two	0
Year Three	0
Total	$ 250.0