Our cash equivalents, marketable securities, and restricted cash equivalents are classified within Level 1 or Level 2 of the fair value hierarchy because their fair values are derived from quoted market prices or alternative pricing sources and models utilizing market observable inputs. Certain other assets are classified within Level 3 because factors used to develop the estimated fair value are unobservable inputs that are not supported by market activity.

The following tables summarize our assets measured at fair value on a recurring basis and the classification by level of input within the fair value hierarchy (in millions):


			Fair Value Measurement at Reporting Date Using
Description	March 31, 2025		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	$	23,437	$	23,437	$	—	$	—
U.S. government securities	494		494		—		—

Time deposits	394		—		394		—
Corporate debt securities	263		—		263		—
Total cash equivalents	24,588		23,931		657		—
Marketable securities:
U.S. government securities	18,381		18,381		—		—
U.S. government agency securities	2,801		2,801		—		—
Corporate debt securities	17,212		—		17,212		—
Marketable equity securities	3,086		3,086		—		—
Total marketable securities	41,480		24,268		17,212		—
Restricted cash equivalents	1,176		1,176		—		—
Other assets	104		—		—		104
Total	$	67,348	$	49,375	$	17,869	$	104


			Fair Value Measurement at Reporting Date Using
Description	December 31, 2024		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	$	36,165	$	36,165	$	—	$	—
U.S. government and agency securities	23		23		—		—

Time deposits	369		—		369		—
Corporate debt securities	114		—		114		—
Total cash equivalents	36,671		36,188		483		—
Marketable securities:
U.S. government securities	14,889		14,889		—		—
U.S. government agency securities	3,053		3,053		—		—
Corporate debt securities	14,758		—		14,758		—
Marketable equity securities	1,226		1,226		—		—
Total marketable securities	33,926		19,168		14,758		—
Restricted cash equivalents	1,193		1,193		—		—
Other assets	101		—		—		101
Total	$	71,891	$	56,549	$	15,241	$	101

The following tables summarize our available-for-sale marketable debt securities and cash equivalents with unrealized losses as of March 31, 2025 and December 31, 2024, aggregated by major security type and the length of time that individual securities have been in a continuous loss position (in millions):


	March 31, 2025
	Less than 12 months				12 months or greater				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. government securities	$	2,863	$	(19)	$	4,134	$	(104)	$	6,997	$	(123)
U.S. government agency securities	248		(1)		1,556		(24)		1,804		(25)
Corporate debt securities	1,479		(7)		5,049		(125)		6,528		(132)
Total	$	4,590	$	(27)	$	10,739	$	(253)	$	15,329	$	(280)


	December 31, 2024
	Less than 12 months				12 months or greater				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. government securities	$	6,860	$	(71)	$	4,330	$	(146)	$	11,190	$	(217)
U.S. government agency securities	435		(2)		2,083		(44)		2,518		(46)
Corporate debt securities	2,989		(26)		6,373		(192)		9,362		(218)
Total	$	10,284	$	(99)	$	12,786	$	(382)	$	23,070	$	(481)