Financing Receivables And Guarantees (Schedule Of Financing Receivables By Portfolio Segment And Class Aging Analysis) (Detail) (USD $) In Millions, unless otherwise specified	Jan. 26, 2013	Jul. 28, 2012	Jan. 28, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Class Of Financing Receivable Thirty One To Sixty Days Past Due	$ 499	$ 250
Class Of Financing Receivable Sixty One To Ninety Days Past Due	74	145
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	492	576
Financing Receivable, Recorded Investment, Past Due	1,065	971
Class Of Financing Receivable Current	7,027	6,655
Capital Leases, Net Investment in Direct Financing Leases	8,092	7,626
Financing Receivable, Recorded Investment, Nonaccrual Status	102	45
Impaired Financing Receivable, Recorded Investment	78	28
Lease Receivables [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Class Of Financing Receivable Thirty One To Sixty Days Past Due	182	151
Class Of Financing Receivable Sixty One To Ninety Days Past Due	34	69
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	230	173
Financing Receivable, Recorded Investment, Past Due	446	393
Class Of Financing Receivable Current	2,998	2,786
Capital Leases, Net Investment in Direct Financing Leases	3,444	3,179	3,049
Financing Receivable, Recorded Investment, Nonaccrual Status	49	23
Impaired Financing Receivable, Recorded Investment	33	14
Loan Receivables [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Class Of Financing Receivable Thirty One To Sixty Days Past Due	12	10
Class Of Financing Receivable Sixty One To Ninety Days Past Due	3	8
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	11	11
Financing Receivable, Recorded Investment, Past Due	26	29
Class Of Financing Receivable Current	1,759	1,767
Capital Leases, Net Investment in Direct Financing Leases	1,785	1,796	1,673
Financing Receivable, Recorded Investment, Nonaccrual Status	32	4
Impaired Financing Receivable, Recorded Investment	32	4
Financed Service Contracts And Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Class Of Financing Receivable Thirty One To Sixty Days Past Due	305	89
Class Of Financing Receivable Sixty One To Ninety Days Past Due	37	68
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	251	392
Financing Receivable, Recorded Investment, Past Due	593	549
Class Of Financing Receivable Current	2,270	2,102
Capital Leases, Net Investment in Direct Financing Leases	2,863	2,651	2,666
Financing Receivable, Recorded Investment, Nonaccrual Status	21	18
Impaired Financing Receivable, Recorded Investment	$ 13	$ 10