Available-for-Sale Debt Investments and Equity Investments - Summary of Available-for-Sale Investments (Details) - USD ($) $ in Millions	Oct. 26, 2019	Jul. 27, 2019
Schedule of Investments [Line Items]
Amortized Cost	$ 19,300	$ 21,590
Gross Unrealized Gains	165	111
Gross Unrealized Losses	(20)	(41)
Fair Value	19,445	21,660
U.S. government securities
Schedule of Investments [Line Items]
Amortized Cost	1,322	808
Gross Unrealized Gains	3	1
Gross Unrealized Losses	(1)	(1)
Fair Value	1,324	808
U.S. government agency securities
Schedule of Investments [Line Items]
Amortized Cost	98	169
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	98	169
Corporate debt securities
Schedule of Investments [Line Items]
Amortized Cost	16,057	19,188
Gross Unrealized Gains	153	103
Gross Unrealized Losses	(11)	(29)
Fair Value	16,199	19,262
U.S. agency mortgage-backed securities
Schedule of Investments [Line Items]
Amortized Cost	1,509	1,425
Gross Unrealized Gains	9	7
Gross Unrealized Losses	(8)	(11)
Fair Value	1,510	$ 1,421
Commercial paper
Schedule of Investments [Line Items]
Amortized Cost	283
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Fair Value	283
Certificates of deposit
Schedule of Investments [Line Items]
Amortized Cost	31
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Fair Value	$ 31

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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