Pension And Postretirement Benefits (Schedule Of Components of Benefit Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Oct. 28, 2012	Oct. 30, 2011
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 14	$ 14
Interest cost	27	31
Expected return on plan assets	(44)	(45)
Recognized net actuarial loss	27	18
Net periodic benefit expense	24	18
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1
Interest cost	4	4
Recognized net actuarial loss	3	2
Net periodic benefit expense	$ 8	$ 7