Pension And Postretirement Benefits Pension And Postretirement Benefits (Schedule Of Pension Plan Assets By Category) (Details) (USD $) In Millions, unless otherwise specified	Jul. 29, 2012	Jul. 31, 2011	Aug. 01, 2010
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	$ 2,118	$ 2,059
Other Items To Reconcile To Fair Value Of Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	0	(5)
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	698	675
Fair Value, Inputs, Level 1 [Member] | Short Term Investment [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	44	5
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	357	396
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	289	267
Fair Value, Inputs, Level 1 [Member] | Domestic Corporate Debt Securities [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 1 [Member] | Foreign Corporate Debt Securities [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 1 [Member] | Domestic Government And Agency Bonds [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 1 [Member] | Foreign Government And Agency Bonds [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 1 [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 1 [Member] | Commingled Funds [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 1 [Member] | Commingled Funds [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 1 [Member] | Commingled Funds [Member] | Blended Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 1 [Member] | Asset-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 1 [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	8	7
Fair Value, Inputs, Level 1 [Member] | Limited Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 1 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	1,385	1,350
Fair Value, Inputs, Level 2 [Member] | Short Term Investment [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	26	46
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 2 [Member] | Domestic Corporate Debt Securities [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	444	414
Fair Value, Inputs, Level 2 [Member] | Foreign Corporate Debt Securities [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	91	88
Fair Value, Inputs, Level 2 [Member] | Domestic Government And Agency Bonds [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	33	9
Fair Value, Inputs, Level 2 [Member] | Foreign Government And Agency Bonds [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	30	31
Fair Value, Inputs, Level 2 [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	75	42
Fair Value, Inputs, Level 2 [Member] | Commingled Funds [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	301	318
Fair Value, Inputs, Level 2 [Member] | Commingled Funds [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	37	62
Fair Value, Inputs, Level 2 [Member] | Commingled Funds [Member] | Blended Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	81	86
Fair Value, Inputs, Level 2 [Member] | Asset-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	14	27
Fair Value, Inputs, Level 2 [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	61	33
Fair Value, Inputs, Level 2 [Member] | Limited Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 2 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	192	194
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	35	39	50
Fair Value, Inputs, Level 3 [Member] | Short Term Investment [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Domestic Corporate Debt Securities [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Foreign Corporate Debt Securities [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Domestic Government And Agency Bonds [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Foreign Government And Agency Bonds [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Commingled Funds [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Commingled Funds [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Commingled Funds [Member] | Blended Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Fair Value, Inputs, Level 3 [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	16	19	18
Fair Value, Inputs, Level 3 [Member] | Limited Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	19	20	24
Fair Value, Inputs, Level 3 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets
Total Before Other Items [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	2,118	2,064
Total Before Other Items [Member] | Short Term Investment [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	70	51
Total Before Other Items [Member] | Equity Securities [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	357	396
Total Before Other Items [Member] | Equity Securities [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	289	267
Total Before Other Items [Member] | Domestic Corporate Debt Securities [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	444	414
Total Before Other Items [Member] | Foreign Corporate Debt Securities [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	91	88
Total Before Other Items [Member] | Domestic Government And Agency Bonds [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	33	9
Total Before Other Items [Member] | Foreign Government And Agency Bonds [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	30	31
Total Before Other Items [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	75	42
Total Before Other Items [Member] | Commingled Funds [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	301	318
Total Before Other Items [Member] | Commingled Funds [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	37	62
Total Before Other Items [Member] | Commingled Funds [Member] | Blended Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	81	86
Total Before Other Items [Member] | Asset-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	14	27
Total Before Other Items [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	85	59
Total Before Other Items [Member] | Limited Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	19	20
Total Before Other Items [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets	$ 192	$ 194