Investments (Maturities of Fixed Income Securities) (Details) (USD $) In Millions	Apr. 30, 2011	Jul. 31, 2010
Amortized Cost	$ 35,938	$ 34,746
Fair Value	36,732	35,280
Fixed Income Securities Maturities Within One Year [Member]
Amortized Cost	13,718
Fair Value	13,744
Fixed Income Securities Maturities Between One and Two Years [Member]
Amortized Cost	15,189
Fair Value	15,250
Fixed Income Securities Maturities Between Two and Five Years [Member]
Amortized Cost	5,933
Fair Value	5,961
Fixed Income Securities Maturities Beyond Five Years [Member]
Amortized Cost	340
Fair Value	357
Fixed Income Securities Maturities Total [Member]
Amortized Cost	35,180
Fair Value	$ 35,312

- Definition

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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