Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 25, 2020	Jul. 27, 2019	Jul. 28, 2018
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of fiscal year	$ 136	$ 129	$ 211
Provisions (benefits)	55	56	(45)
Recoveries (write-offs), net	(48)	(50)	(37)
Foreign exchange and other	0	1	0
Balance at end of fiscal year	143	136	129
Allowance for Financing Receivables
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of fiscal year	126	205	295
Provisions (benefits)	38	(16)	(89)
Recoveries (write-offs), net	(22)	(42)	(6)
Foreign exchange and other	(4)	(21)	5
Balance at end of fiscal year	138	126	205
Deferred Tax Asset Valuation Allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of fiscal year	457	374	244
Provisions (benefits)	279	112	163
Recoveries (write-offs), net	(29)	(20)	(7)
Write-offs	(7)	(8)	(26)
Foreign exchange and other	0	(1)	0
Balance at end of fiscal year	$ 700	$ 457	$ 374