Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Jul. 27, 2019	Jul. 28, 2018
ASSETS
Allowance for doubtful accounts and returns	$ 127	$ 285
Sales-type and direct-financing leases	176	171
Inventory write-downs and capitalization	409	289
Investment provisions	0	54
IPR&D, goodwill, and purchased intangible assets	1,427	63
Deferred revenue	1,150	1,584
Credits and net operating loss carryforwards	1,241	1,087
Share-based compensation expense	164	190
Accrued compensation	342	370
Other	419	408
Gross deferred tax assets	5,455	4,501
Valuation allowance	(457)	(374)
Total deferred tax assets	4,998	4,127
LIABILITIES
Purchased intangible assets	(705)	(753)
Depreciation	(141)	(118)
Unrealized gains on investments	(70)	(33)
Other	(112)	(145)
Total deferred tax liabilities	(1,028)	(1,049)
Total net deferred tax assets	$ 3,970	$ 3,078