Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Jul. 25, 2020	Jul. 27, 2019
ASSETS
Allowance for doubtful accounts and returns	$ 110	$ 127
Sales-type and direct-financing leases	179	176
Inventory write-downs and capitalization	350	409
Deferred foreign income	253	0
IPR&D, goodwill, and purchased intangible assets	1,289	1,427
Deferred revenue	1,182	1,150
Credits and net operating loss carryforwards	1,105	1,241
Share-based compensation expense	135	164
Accrued compensation	353	342
Lease liabilities	240
Other	571	419
Gross deferred tax assets	5,767	5,455
Valuation allowance	(700)	(457)
Total deferred tax assets	5,067	4,998
LIABILITIES
Purchased intangible assets	(577)	(705)
Depreciation	(179)	(141)
Unrealized gains on investments	(119)	(70)
ROU lease assets	(222)
Other	(61)	(112)
Total deferred tax liabilities	(1,158)	(1,028)
Total net deferred tax assets	$ 3,909	$ 3,970