Financing Receivables - Schedule of Financing Receivables (Details) - USD ($) $ in Millions	Jul. 25, 2020	Jul. 27, 2019	Jul. 28, 2018	Jul. 29, 2017
Financing Receivables [Line Items]
Gross	$ 10,894	$ 10,174
Residual value	123
Residual value		142
Unearned income	(114)	(137)
Allowance for credit loss	(138)	(126)	$ (205)	$ (295)
Reported as:
Current	5,051	5,095
Noncurrent	5,714	4,958
Total, net	10,765	10,053
Lease Receivables
Financing Receivables [Line Items]
Gross	2,127	2,367
Residual value	123
Residual value		142
Unearned income	(114)	(137)
Allowance for credit loss	(48)	(46)	(135)	(162)
Reported as:
Current	918	1,029
Noncurrent	1,170	1,297
Total, net	2,088	2,326
Loan Receivables
Financing Receivables [Line Items]
Gross	5,937	5,438
Unearned income	0	0
Allowance for credit loss	(81)	(71)	(60)	(103)
Reported as:
Current	2,692	2,653
Noncurrent	3,164	2,714
Total, net	5,856	5,367
Financed Service Contracts
Financing Receivables [Line Items]
Gross	2,830	2,369
Unearned income	0	0
Allowance for credit loss	(9)	(9)	$ (10)	$ (30)
Reported as:
Current	1,441	1,413
Noncurrent	1,380	947
Total, net	$ 2,821	$ 2,360