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	Jun. 30, 2013		Dec. 31, 2012
Cash, cash equivalents and marketable securities [Line Items]
Total Estimated Fair Value	$ 7,463		$ 11,448
Cash
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	2,488
Total Estimated Fair Value	2,488		2,595
Cash, Cash Equivalents, and Marketable Securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	7,760
Gross Unrealized Gains	9
Gross Unrealized Losses	(7)
Total Estimated Fair Value	7,762		11,547
Restricted Cash, Cash Equivalents and Marketable Securities
Cash, cash equivalents and marketable securities [Line Items]
Total Estimated Fair Value	(299)	[1]	(99)	[1]
Level 1 Securities | Money market funds
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	1,498
Total Estimated Fair Value	1,498		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	729
Gross Unrealized Gains	3
Gross Unrealized Losses	(2)
Total Estimated Fair Value	730		772
Level 2 Securities | U.S. government and agency securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	2,263
Gross Unrealized Gains	2
Gross Unrealized Losses	(3)
Total Estimated Fair Value	2,262		1,810
Level 2 Securities | Corporate debt securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	676
Gross Unrealized Gains	4
Gross Unrealized Losses	(2)
Total Estimated Fair Value	678		725
Level 2 Securities | Asset-backed securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	63
Total Estimated Fair Value	63		49
Level 2 Securities | Other fixed income securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	40
Total Estimated Fair Value	$ 40		$ 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."