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Summary by Major Security Type Cash Cash Equivalents and Marketable Securities Measured at Fair Value on Recurring Basis and Categorized Using Fair Value Hierarchy (Detail) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2013
Dec. 31, 2012
Cash, cash equivalents and marketable securities [Line Items]    
Total Estimated Fair Value $ 7,895 $ 11,448
Cash
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 2,228  
Total Estimated Fair Value 2,228 2,595
Cash, Cash Equivalents, and Marketable Securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 8,059  
Gross Unrealized Gains 14  
Gross Unrealized Losses (2)  
Total Estimated Fair Value 8,071 11,547
Restricted Cash, Cash Equivalents and Marketable Securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Total Estimated Fair Value (176) [1] (99) [1]
Level 1 Securities | Money market funds
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 2,424  
Total Estimated Fair Value 2,424 5,561
Level 1 Securities | Equity securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 3  
Total Estimated Fair Value 3 2
Level 2 Securities | Foreign government and agency securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 679  
Gross Unrealized Gains 6  
Total Estimated Fair Value 685 772
Level 2 Securities | U.S. government and agency securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 1,983  
Gross Unrealized Gains 3  
Gross Unrealized Losses (2)  
Total Estimated Fair Value 1,984 1,810
Level 2 Securities | Corporate debt securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 654  
Gross Unrealized Gains 5  
Total Estimated Fair Value 659 725
Level 2 Securities | Asset-backed securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 55  
Total Estimated Fair Value 55 49
Level 2 Securities | Other fixed income securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 33  
Total Estimated Fair Value $ 33 $ 33
[1] We are required to pledge or otherwise restrict a portion of our cash, cash equivalents, and marketable securities as collateral for standby and trade letters of credit, guarantees, debt and real estate lease agreements. We classify cash and marketable securities with use restrictions of less than twelve months as "Accounts receivable, net and other" and of twelve months or longer as non-current "Other assets" on our consolidated balance sheets. See "Note 3 - Commitments and Contingencies."