Summary by Major Security Type, Cash, Cash Equivalents, and Marketable Securities Measured at Fair Value on a Recurring Basis and Categorized Using the Fair Value Hierarchy (Detail) (USD $) In Millions	Jun. 30, 2011		Dec. 31, 2010
Cash, cash equivalents and marketable securities [Line Items]
Total Estimated Fair Value	$ 6,355		$ 8,762
Level 1 Securities: | Money market funds
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	1,039
Total Estimated Fair Value	1,039		1,882
Level 1 Securities: | Equity securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	2
Gross Unrealized Losses	(1)
Total Estimated Fair Value	1		1
Other fixed income securities | Level 2 Securities:
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	22
Total Estimated Fair Value	22		17
Level 2 Securities: | Foreign government and agency securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	1,422
Gross Unrealized Gains	4
Gross Unrealized Losses	(4)
Total Estimated Fair Value	1,422		2,158
Level 2 Securities: | U.S. government and agency securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	2,514
Gross Unrealized Gains	11
Gross Unrealized Losses	(1)
Total Estimated Fair Value	2,524		3,756
Level 2 Securities: | Corporate debt securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	616
Gross Unrealized Gains	3
Gross Unrealized Losses	(2)
Total Estimated Fair Value	617		459
Level 2 Securities: | Asset-backed securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	28
Total Estimated Fair Value	28		33
Cash
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	850
Total Estimated Fair Value	850		613
Cash, Cash Equivalents, and Marketable Securities
Cash, cash equivalents and marketable securities [Line Items]
Cost or Amortized Cost	6,493
Gross Unrealized Gains	18
Gross Unrealized Losses	(8)
Total Estimated Fair Value	6,503		8,919
Long-term restricted cash, cash equivalents and marketable securities
Cash, cash equivalents and marketable securities [Line Items]
Total Estimated Fair Value	$ (148)	[1]	$ (157)	[1]

[1] We are required to pledge or otherwise restrict a portion of our cash, cash equivalents, and marketable securities as collateral for standby letters of credit, guarantees, debt and real estate lease agreements. We classify cash and marketable securities with use restrictions of twelve months or longer as non-current "Other assets" on our consolidated balance sheets. See "Note 3 - Commitments and Contingencies."