Financial Instruments, Risk Management Activities, and Fair Values (Schedule of interest rate derivatives) (Details) - Interest Rate Contracts [Member] - USD ($) $ in Millions	May 28, 2017	May 29, 2016
Derivative [Line Items]
Derivative, Notional Amount	$ 1,000.0	$ 1,000.0
Average Receive Rate	1.80%	1.80%
Average Pay Rate	1.60%	1.10%
Swap Contract Maturities, Year One	$ 500.0
Swap Contract Maturities, Year Three	500.0
Swap Contract Maturities, Total	$ 1,000.0