Pensions and Other Postretirement Benefits (Details) (USD $)	3 Months Ended		3 Months Ended
	Jul. 29, 2012	Apr. 29, 2012	Jul. 29, 2012 Pension Benefits [Member]	Jul. 27, 2011 Pension Benefits [Member]	Jul. 29, 2012 Other Retiree Benefits [Member]	Jul. 27, 2011 Other Retiree Benefits [Member]	Jul. 29, 2012 Maximum [Member]
Components of net periodic benefit cost
Service cost			$ 7,835,000	$ 8,611,000	$ 1,614,000	$ 1,508,000
Interest cost			32,882,000	35,547,000	2,473,000	2,887,000
Expected return on assets			(62,340,000)	(59,781,000)	0	0
Amortization of prior service cost/(credit)			632,000	498,000	(1,545,000)	(1,530,000)
Amortization of unrecognized loss			18,904,000	21,229,000	451,000	273,000
Settlements			1,014,000	0	0	0
Net periodic benefit (credit)/cost			(1,073,000)	6,104,000	2,993,000	3,138,000
Pensions and Other Post-Retirement Benefits (Textuals) [Abstract]
Benefit obligation recognized for pension benefits as other non-current assets	419,500,000	399,900,000
Employer contribution	15,000,000
Defined Benefit plan, Expected full year combined cash contributions							$ 80,000,000