Financing Receivables And Guarantees (Schedule Of Financing Guarantees Outstanding) (Detail) (USD $) In Millions, unless otherwise specified	Jan. 26, 2013	Jul. 28, 2012
Loss Contingencies [Line Items]
Maximum potential future payments relating to financing guarantees	$ 745	$ 509
Deferred revenue associated with financing guarantees	(484)	(393)
Maximum potential future payments relating to financing guarantees, net of associated deferred revenue	261	116
Channel Partner [Member]
Loss Contingencies [Line Items]
Maximum potential future payments relating to financing guarantees	491	277
Deferred revenue associated with financing guarantees	(267)	(193)
End User [Member]
Loss Contingencies [Line Items]
Maximum potential future payments relating to financing guarantees	254	232
Deferred revenue associated with financing guarantees	$ (217)	$ (200)