Financing Receivables and Operating Leases (Additional Information) (Details) $ in Millions	6 Months Ended
	Jan. 28, 2017 USD ($) rating	Jul. 30, 2016 USD ($)
Financing Receivables And Guarantees [Line Items]
Average lease term	4 years
Deferred revenue	$ 17,086	$ 16,472
Financing receivable, allowance for credit loss and deferred revenue	2,327	2,112
Total financing receivables before allowance for credit loss	$ 9,538	8,805
Threshold for past due receivables	31 days
Unbilled or current financing receivables included in greater than 91 days plus past due	$ 444	670
Financing receivable, 91 days past due and still accruing	$ 316	144
Investment credit risk ratings range lowest | rating	1
Rating at or higher when receivables deemed impaired | rating	10
Rating at or higher when receivables deemed impaired | rating	8
Financed Service Contracts and Other
Financing Receivables And Guarantees [Line Items]
Deferred revenue	$ 1,922	$ 1,716
Maximum
Financing Receivables And Guarantees [Line Items]
Loan receivables term	3 years
Maximum | Financed Service Contracts and Other
Financing Receivables And Guarantees [Line Items]
Financed service contracts term	3 years
Minimum | Financed Service Contracts and Other
Financing Receivables And Guarantees [Line Items]
Financed service contracts term	1 year