Employee Stock Benefit Plans (Summary Of Significant Ranges Of Outstanding And Exercisable Stock Options) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified				9 Months Ended
Apr. 28, 2012	Jul. 30, 2011	Jul. 31, 2010	Apr. 28, 2012 $0.01-15.00 [Member]	Apr. 28, 2012 15.01-18.00 [Member]	Apr. 28, 2012 18.01-20.00 [Member]	Apr. 28, 2012 20.01-25.00 [Member]	Apr. 28, 2012 25.01-35.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Options Outstanding	533	621	732	11	86	154	146	136
Stock Options Outstanding, Weighted-Average Remaining Contractual Life (in Years)	2.76			4.29	2.32	1.16	3.12	4.33
Stock Options Outstanding, Weighted-Average Exercise Price per Share	$ 22.64	$ 21.79	$ 21.39	$ 6.86	$ 17.76	$ 19.29	$ 22.75	$ 30.65
Stock Options Outstanding, Aggregate Intrinsic Value	$ 440			$ 144	$ 190	$ 106
Stock Options Exercisable	519	575		10	86	154	143	126
Stock Options Exercisable, Weighted-Average Exercise Price per Share	$ 22.53	$ 21.37		$ 7.080	$ 17.77	$ 19.29	$ 22.76	$ 30.65
Stock Options Exercisable, Aggregate Intrinsic Value	$ 422			$ 127	$ 189	$ 106
Range of Exercise Price of Stock Options Outstanding and Exercisable, minimum				$ 0.01	$ 15.01	$ 18.01	$ 20.01	$ 25.01
Range of Exercise Price of Stock Options Outstanding and Exercisable, maximum				$ 15.00	$ 18.00	$ 20.00	$ 25.00	$ 35.00

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The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of vested portions of options outstanding and currently exercisable under the option plan as of the balance sheet date.

+ References

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

+ References

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-Name Statement of Financial Accounting Standard (FAS)

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

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The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices pertaining to options outstanding under the plan as of the balance sheet date.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

+ References

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The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan.

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The weighted average period between the balance sheet date and expiration for all awards outstanding under the plan, which may be expressed in a decimal value for number of years.

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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