Pension And Postretirement Benefits Pension And Postretirement Benefits (Schedule of amounts recognized in the Consolidated Balance Sheets) (Details) (USD $) In Millions, unless otherwise specified	Jul. 29, 2012	Jul. 31, 2011
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accrued liabilities	$ (12)	$ (10)
Other liabilities	(618)	(319)
Net amounts recognized	(630)	(329)
Net actuarlai loss	1,486	1,179
Prior service credit	(3)	(3)
Total	1,483	1,176
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accrued liabilities	(27)	(30)
Other liabilities	(386)	(344)
Net amounts recognized	(413)	(374)
Net actuarlai loss	133	95
Prior service credit	(8)	(9)
Total	$ 125	$ 86