Available-for-Sale Debt and Equity Investments - Summary of Available-for-Sale Debt Investments (Details) - USD ($) $ in Millions	Jan. 23, 2021	Jul. 25, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 18,426	$ 17,163
Gross Unrealized Gains	393	454
Gross Unrealized and Credit Losses	(29)
Gross Unrealized Losses		(7)
Fair Value	18,790	17,610
Net unsettled investment sales	39
U.S. government securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,613	2,614
Gross Unrealized Gains	50	71
Gross Unrealized and Credit Losses	0
Gross Unrealized Losses		0
Fair Value	2,663	2,685
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	168	110
Gross Unrealized Gains	0	0
Gross Unrealized and Credit Losses	0
Gross Unrealized Losses		0
Fair Value	168	110
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,516	11,549
Gross Unrealized Gains	296	334
Gross Unrealized and Credit Losses	(26)
Gross Unrealized Losses		(6)
Fair Value	10,786	11,877
U.S. agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,796	1,987
Gross Unrealized Gains	47	49
Gross Unrealized and Credit Losses	(3)
Gross Unrealized Losses		(1)
Fair Value	2,840	2,035
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,730	727
Gross Unrealized Gains	0	0
Gross Unrealized and Credit Losses	0
Gross Unrealized Losses		0
Fair Value	1,730	727
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	603	176
Gross Unrealized Gains	0	0
Gross Unrealized and Credit Losses	0
Gross Unrealized Losses		0
Fair Value	$ 603	$ 176

Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax And Allowance For Credit Loss

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- Definition

Debt Securities, Available-for-sale, Unsettled Sales, Net

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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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Amount 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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