Pension And Postretirement Benefits Pension And Postretirement Benefits (Schedule Of Changes In Fair Value Of Level 3 Investments) (Details) - Pension Plan, Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Jul. 29, 2018	Jul. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 2,183	$ 2,111
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	137	208
Defined Benefit Plan, Fair Value of Plan Assets	2,154	2,183
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	17
Defined Benefit Plan, Fair Value of Plan Assets	10	17
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	38
Defined Benefit Plan, Fair Value of Plan Assets	34	38
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	45	51
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	4	3
Defined Benefit Plan, Purchases	0	2
Defined Benefit Plan, Sale of Plan Assets	(9)	(11)
Defined Benefit Plan, Settlements	0	0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3	0	0
Defined Benefit Plan, Fair Value of Plan Assets	40	45
Fair Value, Inputs, Level 3 [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	7	6
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	2	1
Defined Benefit Plan, Purchases	0	1
Defined Benefit Plan, Sale of Plan Assets	(3)	(1)
Defined Benefit Plan, Settlements	0	0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3	0	0
Defined Benefit Plan, Fair Value of Plan Assets	6	7
Fair Value, Inputs, Level 3 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	38	45
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	2	2
Defined Benefit Plan, Purchases	0	1
Defined Benefit Plan, Sale of Plan Assets	(6)	(10)
Defined Benefit Plan, Settlements	0	0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3	0	0
Defined Benefit Plan, Fair Value of Plan Assets	$ 34	$ 38