Investments (Summary Of Available-For-Sale Investments) (Detail) (USD $) In Millions, unless otherwise specified	Oct. 27, 2012	Jul. 28, 2012
Schedule of Investments [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 39,598	$ 38,263
Available-for-sale Securities, Gross Unrealized Gains	652	669
Available-for-sale Securities, Gross Unrealized Losses	(23)	(15)
Available-for-sale Securities, Fair Value Disclosure	40,227	38,917
Equity Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,263	1,107
Available-for-sale Securities, Gross Unrealized Gains	512	524
Available-for-sale Securities, Gross Unrealized Losses	(12)	(11)
Available-for-sale Securities, Fair Value Disclosure	1,763	1,620
Fixed Income Investments [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Amortized Cost Basis	38,335	37,156
Available-for-sale Securities, Gross Unrealized Gains	140	145
Available-for-sale Securities, Gross Unrealized Losses	(11)	(4)
Available-for-sale Securities, Fair Value Disclosure	38,464	37,297
Fixed Income Investments [Member] \| US Treasury and Government [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Amortized Cost Basis	26,401	24,201
Available-for-sale Securities, Gross Unrealized Gains	22	41
Available-for-sale Securities, Gross Unrealized Losses	(9)	(1)
Available-for-sale Securities, Fair Value Disclosure	26,414	24,241
Fixed Income Investments [Member] \| US Government Agencies Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Amortized Cost Basis	4,441	5,367
Available-for-sale Securities, Gross Unrealized Gains	14	21
Available-for-sale Securities, Fair Value Disclosure	4,455	5,388
Fixed Income Investments [Member] \| Foreign Government Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,388	1,629
Available-for-sale Securities, Gross Unrealized Gains	8	9
Available-for-sale Securities, Fair Value Disclosure	1,396	1,638
Fixed Income Investments [Member] \| Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Amortized Cost Basis	6,105	5,959
Available-for-sale Securities, Gross Unrealized Gains	96	74
Available-for-sale Securities, Gross Unrealized Losses	(2)	(3)
Available-for-sale Securities, Fair Value Disclosure	$ 6,199	$ 6,030

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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