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."