Financing Receivables And Guarantees (Financing Guarantees) (Details) new (USD $) In Millions, unless otherwise specified	Jan. 28, 2012	Jul. 30, 2011
Guarantor Obligations [Line Items]
Maximum potential future payments relating to financing guarantees	$ 600	$ 613
Maximum potential future payments relating to financing guarantees, net of associated deferred revenue	136	117
Deferred Revenue Associated With Financing Guarantees	(464)	(496)
Channel Partner [Member]
Guarantor Obligations [Line Items]
Maximum potential future payments relating to financing guarantees	353	336
Deferred Revenue Associated With Financing Guarantees	(240)	(248)
End User [Member]
Guarantor Obligations [Line Items]
Maximum potential future payments relating to financing guarantees	247	277
Deferred Revenue Associated With Financing Guarantees	$ (224)	$ (248)