Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
Jul. 25, 2020	Jul. 27, 2019	Jul. 28, 2018
Statement of Comprehensive Income [Abstract]
Change in net unrealized gains, tax benefit (expense)	$ (84)	$ (101)	$ (11)
Net (gains) losses reclassified into earnings, tax expense (benefit)	21	6	104
Change in unrealized gains and losses, tax benefit (expense)	0
Change in unrealized gains and losses, tax benefit (expense)		0	(3)
Net (gains) losses reclassified into earnings, tax (benefit) expense	0
Net (gains) losses reclassified into earnings, tax (benefit) expense		0	7
Net change in cumulative translation adjustment and actuarial gains and losses, tax benefit (expense)	$ (5)	$ 15	$ (8)

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- Definition

Amount, before adjustment, of tax expense (benefit) for unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) and unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale.

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- Definition

Amount, before reclassification, of tax expense (benefit) for gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e640-108580

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Amount of tax expense (benefit) for reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

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Amount of tax expense (benefit), before reclassification adjustments, related to increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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