Pension and Postretirement Benefits (Details 8) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 27, 2012	May 29, 2011
Change in the fair value of the Plan assets
Fair Value, Beginning Balance	$ 472.3	$ 153.8
Net Realized and Unrealized Gains (Losses)	42.6	47.3
Net, Purchases and Sales	13.2	271.2
Fair Value, Ending Balance	528.1	472.3
Real estate funds [Member]
Change in the fair value of the Plan assets
Fair Value, Beginning Balance	70.3	61.4
Net Realized and Unrealized Gains (Losses)	2.4	7.5
Net, Purchases and Sales	10.6	1.4
Fair Value, Ending Balance	83.2	70.3
Multi-strategy hedge funds [Member]
Change in the fair value of the Plan assets
Fair Value, Beginning Balance	346.0	22.1
Net Realized and Unrealized Gains (Losses)	38.2	34.1
Net, Purchases and Sales	(5.1)	289.8
Fair Value, Ending Balance	379.1	346.0
Private equity [Member]
Change in the fair value of the Plan assets
Fair Value, Beginning Balance	56.0	39.1
Net Realized and Unrealized Gains (Losses)	2.5	8.1
Net, Purchases and Sales	5.7	8.8
Fair Value, Ending Balance	64.2	56.0
Private energy [Member]
Change in the fair value of the Plan assets
Net Realized and Unrealized Gains (Losses)	(0.5)
Net, Purchases and Sales	2.0
Fair Value, Ending Balance	1.6
Contracts with Insurance Companies [Member]
Change in the fair value of the Plan assets
Fair Value, Beginning Balance		31.2
Net Realized and Unrealized Gains (Losses)		(2.4)
Net, Purchases and Sales		$ (28.8)