Pension and Postretirement Benefits (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 27, 2012	May 29, 2011	May 30, 2010
Pension Benefits [Member]
Changes in benefit obligations and plan assets
Service cost	$ 68.7	$ 59.7	$ 49.8
Interest cost	149.2	147.5	148.1
Expected return on plan assets	(196.0)	(168.0)	(142.3)
Amortization of prior service cost (benefit)	3.0	3.2	3.2
Settlement loss			1.9
Special termination benefits		1.3
Recognized net actuarial (gain) loss	396.9	10.3	165.8
Curtailment loss			0.9
Benefit cost-Company plans	421.8	54.0	227.4
Pension benefit cost multiemployer plans	8.5	9.2	9.7
Total benefit cost	430.3	63.2	237.1
Other Benefits [Member]
Changes in benefit obligations and plan assets
Service cost	0.6	0.6	0.5
Interest cost	13.2	16.3	18.3
Expected return on plan assets		(0.1)	(0.3)
Amortization of prior service cost (benefit)	(13.6)	(9.6)	(9.4)
Recognized net actuarial (gain) loss	7.6	4.6	(0.1)
Benefit cost-Company plans	7.8	11.8	9.0
Total benefit cost	$ 7.8	$ 11.8	$ 9.0