Financing Receivables and Operating Leases (Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jul. 29, 2017	Jul. 29, 2017	Jul. 30, 2016
Financing Receivables And Guarantees [Line Items]
Average lease term		4 years
Threshold for past due receivables		31 days
Unbilled or current financing receivables included in greater than 91 days plus past due	$ 666	$ 666	$ 670
Financing receivable 91 days past due and still accruing	315	$ 315	$ 144
Maximum
Financing Receivables And Guarantees [Line Items]
Loan receivables term		3 years
Financed service contracts term		3 years
Minimum
Financing Receivables And Guarantees [Line Items]
Financed service contracts term		1 year
Financed Service Contracts | Maximum
Financing Receivables And Guarantees [Line Items]
Financed service contracts term		3 years
Financed Service Contracts | Minimum
Financing Receivables And Guarantees [Line Items]
Financed service contracts term		1 year
Lease Receivables
Financing Receivables And Guarantees [Line Items]
Financing receivable reclassification to loan receivables	$ 1,900