Investments (Summary of Available-for-Sale Investments) (Details) - USD ($) $ in Millions	Apr. 28, 2018	Jul. 29, 2017
Schedule of Investments [Line Items]
Amortized Cost	$ 47,856	$ 58,225
Gross Unrealized Gains	539	762
Gross Unrealized Losses	(683)	(203)
Fair Value	47,712	58,784
Net unsettled available-for-sale investments, purchases (sales)	(7)	(30)
Total fixed income securities
Schedule of Investments [Line Items]
Amortized Cost	47,013	57,045
Gross Unrealized Gains	53	208
Gross Unrealized Losses	(679)	(176)
Fair Value	46,387	57,077
Total fixed income securities \| U.S. government securities
Schedule of Investments [Line Items]
Amortized Cost	13,672	19,880
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(141)	(60)
Fair Value	13,531	19,823
Total fixed income securities \| U.S. government agency securities
Schedule of Investments [Line Items]
Amortized Cost	1,166	2,057
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(10)	(5)
Fair Value	1,156	2,052
Total fixed income securities \| Non-U.S. government and agency securities
Schedule of Investments [Line Items]
Amortized Cost	282	389
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(1)
Fair Value	281	388
Total fixed income securities \| Corporate debt securities
Schedule of Investments [Line Items]
Amortized Cost	29,639	31,626
Gross Unrealized Gains	53	202
Gross Unrealized Losses	(454)	(93)
Fair Value	29,238	31,735
Total fixed income securities \| U.S. agency mortgage-backed securities
Schedule of Investments [Line Items]
Amortized Cost	2,009	2,037
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(73)	(17)
Fair Value	1,936	2,023
Total fixed income securities \| Commercial paper
Schedule of Investments [Line Items]
Amortized Cost	195	996
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	195	996
Total fixed income securities \| Certificates of deposit
Schedule of Investments [Line Items]
Amortized Cost	50	60
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	50	60
Publicly traded equity securities
Schedule of Investments [Line Items]
Amortized Cost	843	1,180
Gross Unrealized Gains	486	554
Gross Unrealized Losses	(4)	(27)
Fair Value	$ 1,325	$ 1,707

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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