Annual report pursuant to Section 13 and 15(d)

Assets And Liabilities Measured At Fair Value (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details)

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Assets And Liabilities Measured At Fair Value (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2012
Dec. 31, 2011
Short term marketable securities $ 67 $ 299
Fair Value, Inputs, Level 1 [Member]
   
Cash Equivalents, at Carrying Value 1,224 1,845
Short term marketable securities 0 0
Available-for-sale securities 978 1,441
Fair Value, Inputs, Level 2 [Member]
   
Cash Equivalents, at Carrying Value 0 21
Short term marketable securities 67 299
Available-for-sale securities 383 410
Fair Value, Inputs, Level 3 [Member]
   
Cash Equivalents, at Carrying Value 0 0
Short term marketable securities 0 0
Available-for-sale securities 0 0
Estimate of Fair Value, Fair Value Disclosure [Member]
   
Cash Equivalents, at Carrying Value 1,224 1,866
Short term marketable securities 67 299
Available-for-sale securities $ 1,361 $ 1,851