Available-For-Sale Investments (Summary Of Fair Value Of Available-For-Sale Investments) (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
U.S. Government And Agencies [Member]
Schedule Of Available-For-Sale Securities [Line Items]
Amortized cost	$ 1,507	$ 1,734
Fair value	1,512	1,737
Asset-Backed Securities [Member]
Schedule Of Available-For-Sale Securities [Line Items]
Amortized cost	59	64
Fair value	38	45
Other Debt Securities [Member]
Schedule Of Available-For-Sale Securities [Line Items]
Amortized cost	6	11
Fair value	8	15
Long-Term Investments [Member]
Schedule Of Available-For-Sale Securities [Line Items]
Amortized cost	59	64
Fair value	38	45
Short-Term Investments [Member]
Schedule Of Available-For-Sale Securities [Line Items]
Amortized cost	1,513	1,745
Fair value	$ 1,520	$ 1,752

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 7: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 16

-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.

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-Publisher FASB

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+ Details