Pension And Postretirement Benefits (Pension Plan Assets Changes In Fair Value Of Level 3 Investments) (Details) (Pension Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 28, 2013	Jul. 29, 2012
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at beginning of year	$ 2,118	$ 2,059
Actual Return on Plan Assets	246	149
Fair Value of Plan Assets at end of year	2,275	2,118
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at beginning of year	35	39
Actual Return on Plan Assets	2	4
Purchase of Plan Assets	30	0
Sale of Plan Assets	(3)	(8)
Settlements, Plan Assets	0	0
Transfers Between Measurement Levels	(16)	0
Fair Value of Plan Assets at end of year	48	35
Fair Value, Inputs, Level 3 [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at beginning of year	16	19
Actual Return on Plan Assets	0	2
Purchase of Plan Assets	0	0
Sale of Plan Assets	0	(5)
Settlements, Plan Assets	0	0
Transfers Between Measurement Levels	(16)	0
Fair Value of Plan Assets at end of year	0	16
Fair Value, Inputs, Level 3 [Member] | Limited Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at beginning of year	19	20
Actual Return on Plan Assets	2	2
Purchase of Plan Assets	0	0
Sale of Plan Assets	(3)	(3)
Settlements, Plan Assets	0	0
Transfers Between Measurement Levels	0	0
Fair Value of Plan Assets at end of year	18	19
Fair Value, Inputs, Level 3 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at beginning of year	0	0
Actual Return on Plan Assets	0	0
Purchase of Plan Assets	30	0
Sale of Plan Assets	0	0
Settlements, Plan Assets	0	0
Transfers Between Measurement Levels	0	0
Fair Value of Plan Assets at end of year	$ 30	$ 0