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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
Dec. 31, 2012
Dec. 31, 2011
Cash, cash equivalents and marketable securities [Line Items]    
Total Estimated Fair Value $ 11,448 $ 9,576
Cash
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 2,595 1,207
Total Estimated Fair Value 2,595 1,207
Cash, Cash Equivalents, and Marketable Securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 11,531 9,719
Gross Unrealized Gains 18 20
Gross Unrealized Losses (2) (7)
Total Estimated Fair Value 11,547 9,732
Restricted Cash, Cash Equivalents and Marketable Securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Total Estimated Fair Value (99) [1] (156) [1]
Level 1 Securities | Money market funds
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 5,561 3,651
Total Estimated Fair Value 5,561 3,651
Level 1 Securities | Equity securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 2 2
Gross Unrealized Losses   (1)
Total Estimated Fair Value 2 1
Level 2 Securities | Foreign government and agency securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 763 1,627
Gross Unrealized Gains 9 14
Gross Unrealized Losses   (1)
Total Estimated Fair Value 772 1,640
Level 2 Securities | U.S. government and agency securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 1,809 2,592
Gross Unrealized Gains 3 3
Gross Unrealized Losses (2) (2)
Total Estimated Fair Value 1,810 2,593
Level 2 Securities | Corporate debt securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 719 562
Gross Unrealized Gains 6 3
Gross Unrealized Losses   (2)
Total Estimated Fair Value 725 563
Level 2 Securities | Asset-backed securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 49 56
Gross Unrealized Losses   (1)
Total Estimated Fair Value 49 55
Level 2 Securities | Other fixed income securities
    
Cash, cash equivalents and marketable securities [Line Items]    
Cost or Amortized Cost 33 22
Total Estimated Fair Value $ 33 $ 22
[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 8-Commitments and Contingencies."