Pension and Other Postretirement Benefit Plans 9 (Details) (USD $)	12 Months Ended
	Apr. 29, 2012	Apr. 27, 2011	Apr. 28, 2010
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 2,791,800,000	$ 2,602,000,000
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Accumulated Benefit Obligation	630,300,000	154,300,000
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation	642,300,000	175,000,000
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Fair Value of Plan Assets	452,900,000	27,000,000
Defined Benefit Plan, Contributions by Employer	23,500,000
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(353,100,000)	95,500,000
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	87,300,000	82,200,000
Defined Benefit Plan, Contributions by Employer	23,469,000	22,411,000
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	80,000,000
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(18,000,000)	7,500,000
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	5,000,000	3,600,000
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	7.10%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4.80%
Defined Benefit Plan, Contributions by Employer	18,862,000	16,164,000
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	17,600,000
Prescription Drug Subsidy Receipts Current Year	1,100,000
P P A C A Reduction In Tax Benefits Of Medicare Part D Subsidy			$ 3,900,000
P P A C A Reduction In Tax Benefits Of Medicare Part D Subsidy Per Share			$ 0.01