Fair Value Measurements

9 Months Ended

Sep. 30, 2012

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

Assets measured at fair value on a recurring basis are summarized below (in millions):

			Fair Value Measurement at Reporting Date Using
Description	September 30, 2012		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents:
Money market funds	$	730	$	730	$	—	$	—
U.S. government securities	234		234		—		—
U.S. government agency securities	208		208		—		—
Marketable securities:
U.S. government securities	5,644		5,644		—		—
U.S. government agency securities	2,330		2,330		—		—
Total cash equivalents and marketable securities	$	9,146	$	9,146	$	—	$	—

			Fair Value Measurement at Reporting Date Using
Description	December 31, 2011		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents:
Money market funds	$	892	$	892	$	—	$	—
U.S. government securities	60		60		—		—
U.S. government agency securities	50		50		—		—
Marketable securities:
U.S. government securities	1,415		1,415		—		—
U.S. government agency securities	981		981		—		—
Total cash equivalents and marketable securities	$	3,398	$	3,398	$	—	$	—

Gross unrealized gains or losses for cash equivalents and marketable securities as of September 30, 2012 and December 31, 2011 were not material.

The following table classifies our marketable securities by contractual maturities as of September 30, 2012 (in millions):

	Fair Value
Due in one year	$	5,658
Due in one to two years	2,316
	$	7,974