Fair Value of Financial Instruments (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Investments in Marketable Securities (Amounts in Paragraph) [Abstract]
Marketable securities included in prepaid expenses and other current assets		$ 250
Marketable securities included in other non-current assets	261	223
Notional values of foreign currency forward contracts for designated instruments	164	233
Cash Flow Hedges
Investments in Marketable Securities (Amounts in Paragraph) [Abstract]
Notional values of foreign currency forward contracts for designated instruments	$ 110	$ 145

Total common and preferred stock (which is neither mandatorily redeemable nor redeemable at the option of the holder) equity securities that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time, usually less than one year or the normal operating cycle, whichever is longer) or for equity securities formerly categorized as available-for-sale or held-to-maturity which the entity held as of the date it opted to account for such securities at fair value. An enterprise may also categorize such a security as trading without the intent to sell it in the near term assuming the decision to categorize the security as trading occurred at acquisition.

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-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph 12

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-Publisher FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=6526789

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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-URI http://asc.fasb.org/extlink&oid=6511694

Reference 7: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details