Pension And Postretirement Benefits (Schedule Of Components of Benefit Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	May 03, 2015	Apr. 27, 2014	May 03, 2015	Apr. 27, 2014
Defined Benefit Plan Disclosure [Line Items]
Curtailment loss			$ 7
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	8	11	22	32
Interest cost	26	29	79	87
Expected return on plan assets	(43)	(44)	(130)	(133)
Amortization of prior service cost	(1)	(1)	(1)	(1)
Recognized net actuarial loss	21	20	63	58
Curtailment loss	1	0	1	0
Settlement charge	0	18	0	18
Net periodic benefit expense	12	33	34	61
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	2	2
Interest cost	3	4	11	13
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	0	(1)	(1)
Recognized net actuarial loss	3	2	9	9
Curtailment loss	6	0	6	0
Settlement charge	0	0	0	0
Net periodic benefit expense	$ 13	$ 7	$ 27	$ 23