CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value, by Balance Sheet Grouping

The following table summarizes, by major security type, our cash, cash equivalents, and marketable securities that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy (in millions):

	December 31, 2012
	Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Total Estimated Fair Value
Cash	$	2,595		—		—		$	2,595
Level 1 securities:
Money market funds		5,561		—		—			5,561
Equity securities		2		—		—			2
Level 2 securities:
Foreign government and agency securities		763		9		—			772
U.S. government and agency securities		1,809		3		(2	)		1,810
Corporate debt securities		719		6		—			725
Asset-backed securities		49		—		—			49
Other fixed income securities		33		—		—			33
	$	11,531	$	18	$	(2	)	$	11,547
Less: Restricted cash, cash equivalents, and marketable securities (1)									(99	)
Total cash, cash equivalents, and marketable securities								$	11,448

	December 31, 2011
	Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Total Estimated Fair Value
Cash	$	1,207		—		—		$	1,207
Level 1 securities:
Money market funds		3,651		—		—			3,651
Equity securities		2		—		(1	)		1
Level 2 securities:
Foreign government and agency securities		1,627		14		(1	)		1,640
U.S. government and agency securities		2,592		3		(2	)		2,593
Corporate debt securities		562		3		(2	)		563
Asset-backed securities		56		—		(1	)		55
Other fixed income securities		22		—		—			22
	$	9,719	$	20	$	(7	)	$	9,732
Less: Restricted cash, cash equivalents, and marketable securities (1)									(156	)
Total cash, cash equivalents, and marketable securities								$	9,576

(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.”

Realized Gain (Loss) on Investments

The following table summarizes gross gains and gross losses realized on sales of available-for-sale marketable securities (in millions):

	Year Ended December 31,
	2012		2011		2010
Realized gains	$	20	$	15	$	5
Realized losses		10		11		4

Investments Classified by Contractual Maturity Date

The following table summarizes the maturities of our cash equivalent and marketable fixed-income securities as of December 31, 2012 (in millions):

	Amortized Cost		Estimated Fair Value
Due within one year	$	6,689	$	6,691
Due after one year through five years		1,968		1,981
Due after five years		277		278
	$	8,934	$	8,950