Financing Receivables - Additional Information (Details) $ in Millions	6 Months Ended
	Jan. 25, 2020 USD ($) rating	Jul. 27, 2019 USD ($)
Financing Receivables And Guarantees [Line Items]
Lease receivables terms, on average	4 years
Loan receivables term	3 years
Threshold for past due receivables	31 days
Financing receivable, 91 days past due and still accruing | $	$ 201	$ 215
Investment credit risk ratings range lowest (rating)	1
Highest rating when receivables are deemed impaired (rating)	10
Rating at or higher when receivables deemed impaired (rating)	8
Minimum | Financed Service Contracts
Financing Receivables And Guarantees [Line Items]
Financed service contracts term	1 year
Maximum | Financed Service Contracts
Financing Receivables And Guarantees [Line Items]
Financed service contracts term	3 years