Derivative Instruments (Effect of Derivative Instruments Not Designated as Fair Value Hedges on Consolidated Statement of Operations Summary) (Details) (Derivatives Not Designated as Hedging Instruments [Member], USD $) In Millions	3 Months Ended		9 Months Ended
	Apr. 30, 2011	May 01, 2010	Apr. 30, 2011	May 01, 2010
Gains (losses) recognized in income	$ 135	$ (108)	$ 297	$ (34)
Foreign Currency Derivatives [Member] | Other Income Net [Member]
Gains (losses) recognized in income	114	(118)	244	(69)
Equity Derivatives [Member] | Other Income Net [Member]
Gains (losses) recognized in income	8	5	16	12
Operating Expenses [Member] | Total Return Swaps-Deferred Compensation [Member]
Gains (losses) recognized in income	$ 13	$ 5	$ 37	$ 23