Pension And Postretirement Benefits (Schedule Of Components of Benefit Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 27, 2013	Jan. 29, 2012	Jan. 27, 2013	Jan. 29, 2012
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 14	$ 13	$ 28	$ 27
Interest cost	27	30	54	61
Expected return on plan assets	(45)	(44)	(89)	(89)
Amortization of Prior Service Cost (Credit)	(1)	0	(1)	0
Recognized net actuarial loss	27	19	54	37
Curtailment loss	3		3
Net periodic benefit expense	25	18	49	36
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	2	2
Interest cost	4	5	8	9
Expected return on plan assets	0	0	0	0
Amortization of Prior Service Cost (Credit)	(1)	(1)	(1)	(1)
Recognized net actuarial loss	4	2	7	4
Net periodic benefit expense	$ 8	$ 7	$ 16	$ 14