Revenue - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 26, 2019	Oct. 27, 2018	Jul. 27, 2019
Revenue from Contract with Customer [Abstract]
Payment terms	30 days
Accounts receivable, net	$ 4,878		$ 5,491
Total deferred revenue	18,602		18,467
Revenue recognized	3,700
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	24,900		25,300
Total deferred sales commissions	707		750
Amortization of sales commissions, expense	116	$ 112
Unbilled Contract Revenue
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	6,300		6,800
Software and Service Agreements
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total contract assets	$ 954		$ 860