Available-for-Sale Debt and Equity Investments - Summary of Available-for-Sale Debt Investments (Details) - USD ($) $ in Millions	Oct. 24, 2020	Jul. 25, 2020
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	$ 18,823	$ 17,163
Gross Unrealized Gains	400	454
Gross Unrealized and Credit Losses	(33)
Gross Unrealized Losses		(7)
Fair Value	19,190	17,610
Net unsettled investment sales	57
U.S. government securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	2,656	2,614
Gross Unrealized Gains	61	71
Gross Unrealized and Credit Losses	0
Gross Unrealized Losses		0
Fair Value	2,717	2,685
U.S. government agency securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	178	110
Gross Unrealized Gains	0	0
Gross Unrealized and Credit Losses	0
Gross Unrealized Losses		0
Fair Value	178	110
Corporate debt securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	11,266	11,549
Gross Unrealized Gains	298	334
Gross Unrealized and Credit Losses	(27)
Gross Unrealized Losses		(6)
Fair Value	11,537	11,877
U.S. agency mortgage-backed securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	2,494	1,987
Gross Unrealized Gains	41	49
Gross Unrealized and Credit Losses	(6)
Gross Unrealized Losses		(1)
Fair Value	2,529	2,035
Commercial paper
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	1,712	727
Gross Unrealized Gains	0	0
Gross Unrealized and Credit Losses	0
Gross Unrealized Losses		0
Fair Value	1,712	727
Certificates of deposit
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	517	176
Gross Unrealized Gains	0	0
Gross Unrealized and Credit Losses	0
Gross Unrealized Losses		0
Fair Value	$ 517	$ 176

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

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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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