Financing Receivables and Operating Leases (Additional Information) (Details) $ in Millions	6 Months Ended
	Jan. 27, 2018 USD ($) rating	Jul. 29, 2017 USD ($)
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 | $	$ 462	$ 666
Financing receivable, 91 days past due and still accruing | $	$ 358	$ 315
Investment credit risk ratings range lowest	1
Highest rating when receivables are deemed impaired	10
Rating at or higher when receivables deemed impaired	8
Maximum
Financing Receivables And Guarantees [Line Items]
Loan receivables term	3 years
Maximum | Financed Service Contracts
Financing Receivables And Guarantees [Line Items]
Financed service contracts term	3 years
Minimum | Financed Service Contracts
Financing Receivables And Guarantees [Line Items]
Financed service contracts term	1 year