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. 30, 2017	Jul. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 2,111	$ 2,316
Defined Benefit Plan, Actual Return on Plan Assets	208	54
Defined Benefit Plan, Fair Value of Plan Assets	2,183	2,111
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	19
Defined Benefit Plan, Fair Value of Plan Assets	17	19
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	45
Defined Benefit Plan, Fair Value of Plan Assets	38	45
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	51	45
Defined Benefit Plan, Actual Return on Plan Assets	3	2
Defined Benefit Plan, Purchase of Plan Assets	2	5
Defined Benefit Plan, Sale of Plan Assets	(11)	(1)
Defined Benefit Plan, Settlements	0	0
Defined Benefit Plan, Transfers Between Measurement Levels	0	0
Defined Benefit Plan, Fair Value of Plan Assets	45	51
Fair Value, Inputs, Level 3 [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6	6
Defined Benefit Plan, Actual Return on Plan Assets	1	1
Defined Benefit Plan, Purchase of Plan Assets	1	0
Defined Benefit Plan, Sale of Plan Assets	(1)	(1)
Defined Benefit Plan, Settlements	0	0
Defined Benefit Plan, Transfers Between Measurement Levels	0	0
Defined Benefit Plan, Fair Value of Plan Assets	7	6
Fair Value, Inputs, Level 3 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	45	39
Defined Benefit Plan, Actual Return on Plan Assets	2	1
Defined Benefit Plan, Purchase of Plan Assets	1	5
Defined Benefit Plan, Sale of Plan Assets	(10)	0
Defined Benefit Plan, Settlements	0	0
Defined Benefit Plan, Transfers Between Measurement Levels	0	0
Defined Benefit Plan, Fair Value of Plan Assets	$ 38	$ 45