Available-for-Sale Debt Investments and Equity Investments (Summary of Available-for-Sale Investments) (Details) - USD ($) $ in Millions	Apr. 27, 2019	Jul. 28, 2018
Schedule of Investments [Line Items]
Amortized Cost	$ 24,491	$ 37,512
Gross Unrealized Gains	44	44
Gross Unrealized Losses	(148)	(547)
Fair Value	24,387	37,009
Net unsettled, available-for-sale investments purchases (sales), net	1	(1,500)
U.S. government securities
Schedule of Investments [Line Items]
Amortized Cost	1,455	7,318
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(4)	(43)
Fair Value	1,452	7,275
U.S. government agency securities
Schedule of Investments [Line Items]
Amortized Cost	264	732
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(5)
Fair Value	263	727
Non-U.S. government and agency securities
Schedule of Investments [Line Items]
Amortized Cost		209
Gross Unrealized Gains		0
Gross Unrealized Losses		(1)
Fair Value		208
Corporate debt securities
Schedule of Investments [Line Items]
Amortized Cost	21,307	27,765
Gross Unrealized Gains	40	44
Gross Unrealized Losses	(115)	(445)
Fair Value	21,232	27,364
U.S. agency mortgage-backed securities
Schedule of Investments [Line Items]
Amortized Cost	1,465	1,488
Gross Unrealized Gains	3	0
Gross Unrealized Losses	(28)	(53)
Fair Value	$ 1,440	$ 1,435

Net Unsettled, Available-For-Sale Investments Purchases (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).

+ References

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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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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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