Pension And Postretirement Benefits (Schedule Of Components of Benefit Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Feb. 01, 2015	Jan. 26, 2014	Feb. 01, 2015	Jan. 26, 2014
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7	$ 10	$ 14	$ 21
Interest cost	26	29	53	58
Expected return on plan assets	(43)	(44)	(87)	(89)
Amortization of prior service cost	0	0	0	0
Recognized net actuarial loss	21	19	42	38
Net periodic benefit expense	11	14	22	28
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	0	1	1
Interest cost	4	5	8	9
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(1)	(1)	(1)	(1)
Recognized net actuarial loss	3	4	6	7
Net periodic benefit expense	$ 7	$ 8	$ 14	$ 16