Financing Receivables And Guarantees (Schedule Of Financing Receivables By Portfolio Segment And Class Aging Analysis) (Detail) (USD $) In Millions, unless otherwise specified	Oct. 27, 2012	Jul. 28, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Class Of Financing Receivable Thirty One To Sixty Days Past Due	$ 158	$ 250
Class Of Financing Receivable Sixty One To Ninety Days Past Due	206	145
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	706	576
Financing Receivable, Recorded Investment, Past Due	1,070	971
Class Of Financing Receivable Current	6,725	6,655
Class Of Financing Receivables Net Of Unearned Income	7,795	7,626
Financing Receivable, Recorded Investment, Nonaccrual Status	45	45
Impaired Financing Receivable, Recorded Investment	28	28
Lease Receivables [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Class Of Financing Receivable Thirty One To Sixty Days Past Due	88	151
Class Of Financing Receivable Sixty One To Ninety Days Past Due	76	69
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	206	173
Financing Receivable, Recorded Investment, Past Due	370	393
Class Of Financing Receivable Current	2,970	2,786
Financing Receivable, Recorded Investment, Nonaccrual Status	23	23
Impaired Financing Receivable, Recorded Investment	15	14
Loan Receivables [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Class Of Financing Receivable Thirty One To Sixty Days Past Due	6	10
Class Of Financing Receivable Sixty One To Ninety Days Past Due	0	8
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	23	11
Financing Receivable, Recorded Investment, Past Due	29	29
Class Of Financing Receivable Current	1,787	1,767
Class Of Financing Receivables Net Of Unearned Income	1,816	1,796
Financing Receivable, Recorded Investment, Nonaccrual Status	6	4
Impaired Financing Receivable, Recorded Investment	6	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	64	89
Class Of Financing Receivable Sixty One To Ninety Days Past Due	130	68
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	477	392
Financing Receivable, Recorded Investment, Past Due	671	549
Class Of Financing Receivable Current	1,968	2,102
Class Of Financing Receivables Net Of Unearned Income	2,639	2,651
Financing Receivable, Recorded Investment, Nonaccrual Status	16	18
Impaired Financing Receivable, Recorded Investment	7	10
Gross Receivables, Net of Unearned Income [Member] | Lease Receivables [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Class Of Financing Receivables Net Of Unearned Income	$ 3,340	$ 3,179