Revenue - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 25, 2020	Jan. 26, 2019	Jan. 25, 2020	Jan. 26, 2019	Jul. 27, 2019
Revenue from Contract with Customer [Abstract]
Payment terms			30 days
Accounts receivable, net	$ 4,330		$ 4,330		$ 5,491
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	24,900		24,900		25,300
Total deferred revenue	18,686		18,686		18,467
Revenue recognized	2,900		6,600
Total deferred sales commissions	708		708		750
Amortization of sales commissions, expense	122	$ 100	238	$ 212
Unbilled Contract Revenue
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	6,200		6,200		6,800
Software and Service Agreements
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total contract assets	$ 966		$ 966		$ 860