Pension And Postretirement Benefits (Schedule of Change in Benefit Obligation) (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 30, 2017	Jul. 31, 2016	Aug. 02, 2015
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Benefit Obligation	$ 2,626	$ 2,569
Defined Benefit Plan, Service Cost	26	26	$ 28
Defined Benefit Plan, Interest Cost	86	98	105
Defined Benefit Plan, Actuarial Gain (Loss)	(134)	210
Defined Benefit Plan, Contributions by Plan Participants	0	0
Defined Benefit Plan, Plan Amendments	0	0
Defined Benefit Plan, Benefits Paid	(164)	(116)
Defined Benefit Plan, Settlements, Benefit Obligation	0	(160)
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received	0	0
Defined Benefit Plan, Other Changes	(3)	(6)
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)	13	5
Defined Benefit Plan, Benefit Obligation	2,450	2,626	2,569
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Benefit Obligation	313	392
Defined Benefit Plan, Service Cost	1	1	2
Defined Benefit Plan, Interest Cost	10	15	15
Defined Benefit Plan, Actuarial Gain (Loss)	(14)	23
Defined Benefit Plan, Contributions by Plan Participants	1	1
Defined Benefit Plan, Plan Amendments	(12)	(93)
Defined Benefit Plan, Benefits Paid	(26)	(30)
Defined Benefit Plan, Settlements, Benefit Obligation	0	0
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received	3	4
Defined Benefit Plan, Other Changes	0	0
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)	0	0
Defined Benefit Plan, Benefit Obligation	$ 276	$ 313	$ 392