Marketable Securities (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2011 D M	Dec. 31, 2010
Marketable securities classification
Current marketable securities	$ 1,486	$ 1,101
Non-current marketable securities	443	540
Total marketable securities	1,929	1,641
Gross unrealized losses on marketable securities (pre-tax)	11	9
Gross unrealized gains on marketable securities (pre-tax)	2	5
U.S. government agency securities
Marketable securities classification
Current marketable securities	257	246
Non-current marketable securities	132	63
Foreign government agency securities
Marketable securities classification
Current marketable securities		52
Non-current marketable securities	3	3
Corporate debt securities
Marketable securities classification
Current marketable securities	389	280
Non-current marketable securities	106	192
Commercial paper
Marketable securities classification
Current marketable securities	138	55
Certificates of deposit/time deposits
Marketable securities classification
Current marketable securities	117	29
U.S. treasury securities
Marketable securities classification
Current marketable securities		55
Non-current marketable securities	34	44
U.S. municipal securities
Marketable securities classification
Current marketable securities	6	20
Non-current marketable securities	3	3
Asset-backed securities:
Marketable securities classification
Current marketable securities	577	364
Non-current marketable securities	160	228
Estimated fair value of current and long-term asset-backed securities	737
Number of securities rated A1 or A3	2
Estimated fair value of asset-backed securities rated A1 or A3	7
Asset-backed securities Automobile loan related
Marketable securities classification
Current marketable securities	388	253
Non-current marketable securities	81	144
Asset-backed securities Credit card related
Marketable securities classification
Current marketable securities	144	79
Non-current marketable securities	56	70
Asset-backed securities Equipment lease related
Marketable securities classification
Current marketable securities	35	24
Non-current marketable securities	23	14
Asset-backed securities Other asset-backed securities
Marketable securities classification
Current marketable securities	10	8
Auction rate securities
Marketable securities classification
Non-current marketable securities	5	7
Percentage of interests in auction rate securities to portfolio, maximum (as a percent)	1.00%
Estimated fair value of auction-rate securities	5	7
Gross unrealized losses (pre-tax) within accumulated other comprehensive income related to auction rate securities	8	6
Minimum period that auction rate securities have been in a loss position (in months)	12
Pre-determined intervals during which liquidity for auction rate securities is typically provided 1 (in days)	7
Pre-determined intervals during which liquidity for auction rate securities is typically provided 2 (in days)	28
Pre-determined intervals during which liquidity for auction rate securities is typically provided 3 (in days)	35
Pre-determined intervals during which liquidity for auction rate securities is typically provided 4 (in days)	90
Other securities
Marketable securities classification
Current marketable securities	$ 2

Represents the gross unrealized losses (pre-tax) within accumulated other comprehensive income related to auction rate securities.

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Represents pre-determined intervals (in days) during which liquidity for auction rate securities is typically provided by an auction process that resets the applicable interest rate 1.

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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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