Pension and Other Postretirement Benefit Plans 7 (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 28, 2013	Apr. 29, 2012
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at the end of the year	$ 3,379,143	$ 3,140,834
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	58,701	96,938
Fair value of plan assets at the beginning of the year	226,720	140,744
Transfers In	(10,498)	10,138
Dispositions	(3,605)	(21,262)
Realized Gain /(Loss)	(6,637)	753
Unrealized Gain /(Loss)	3,436	(591)
Fair value of plan assets at the end of the year	268,117	226,720
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at the end of the year	980,296	981,496
Fixed Income Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	0	0
Fair value of plan assets at the beginning of the year	10,486	9,649
Transfers In	0	0
Dispositions	0	0
Realized Gain /(Loss)	0	0
Unrealized Gain /(Loss)	850	837
Fair value of plan assets at the end of the year	11,336	10,486
Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at the end of the year	256,781	216,234
Other Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	58,701	96,938
Fair value of plan assets at the beginning of the year	216,234	131,095
Transfers In	(10,498)	10,138
Dispositions	(3,605)	(21,262)
Realized Gain /(Loss)	(6,637)	753
Unrealized Gain /(Loss)	2,586	(1,428)
Fair value of plan assets at the end of the year	$ 256,781	$ 216,234