Pensions and Other Postretirement Benefits (Details) (USD $)	6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Oct. 26, 2011	Apr. 27, 2011	Oct. 26, 2011 Maximum [Member]	Oct. 26, 2011 Pension Benefits [Member]	Oct. 27, 2010 Pension Benefits [Member]	Oct. 26, 2011 Pension Benefits [Member]	Oct. 27, 2010 Pension Benefits [Member]	Oct. 26, 2011 Other Retiree Benefits [Member]	Oct. 27, 2010 Other Retiree Benefits [Member]	Oct. 26, 2011 Other Retiree Benefits [Member]	Oct. 27, 2010 Other Retiree Benefits [Member]
Components of net periodic benefit cost
Service cost				$ 8,445,000	$ 8,096,000	$ 17,056,000	$ 15,833,000	$ 1,489,000	$ 1,567,000	$ 2,997,000	$ 3,128,000
Interest cost				34,939,000	35,512,000	70,486,000	69,791,000	2,860,000	3,162,000	5,747,000	6,316,000
Expected return on assets				(58,756,000)	(57,278,000)	(118,537,000)	(112,570,000)	0	0	0	0
Amortization of prior service cost/(credit)				495,000	617,000	993,000	1,208,000	(1,532,000)	(1,291,000)	(3,062,000)	(2,581,000)
Amortization of unrecognized loss				20,937,000	19,388,000	42,166,000	38,356,000	274,000	401,000	547,000	802,000
Net periodic benefit cost				6,060,000	6,335,000	12,164,000	12,618,000	3,091,000	3,839,000	6,229,000	7,665,000
Pensions and Other Post-Retirement Benefits (Textuals) [Abstract]
Benefit obligation recognized for pension benefits as other non-current assets	662,500,000	644,600,000
Employer contribution	8,000,000
Defined Benefit plan, Expected full year combined cash contributions			$ 30,000,000