Financing Receivables - Schedule of Financing Receivables (Details) - USD ($) $ in Millions	Jan. 23, 2021	Oct. 24, 2020	Jul. 25, 2020	Jan. 25, 2020	Oct. 26, 2019	Jul. 27, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	$ 10,257		$ 10,894
Residual value	115		123
Unearned income	(97)		(114)
Allowance for credit loss	(148)	$ (154)	(138)	$ (145)	$ (133)	$ (126)
Total, net	10,127		10,765
Current	5,027		5,051
Noncurrent	5,100		5,714
Lease Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	1,865		2,127
Residual value	115		123
Unearned income	(97)		(114)
Allowance for credit loss	(43)	(46)	(48)	(42)	(43)	(46)
Total, net	1,840		2,088
Current	868		918
Noncurrent	972		1,170
Loan Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	5,817		5,937
Unearned income	0		0
Allowance for credit loss	(96)	(101)	(81)	(95)	(81)	(71)
Total, net	5,721		5,856
Current	2,746		2,692
Noncurrent	2,975		3,164
Financed Service Contracts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	2,575		2,830
Unearned income	0		0
Allowance for credit loss	(9)	$ (7)	(9)	$ (8)	$ (9)	$ (9)
Total, net	2,566		2,821
Current	1,413		1,441
Noncurrent	$ 1,153		$ 1,380