We have cash deposits with financial institutions globally. As part of our cash management strategy, we concentrate cash deposits with large financial institutions subject to the strictest regulations and our marketable securities are held in diversified highly rated securities.

We classify our cash equivalents and marketable debt securities within Level 1 or Level 2 because we use quoted market prices or alternative pricing sources and models utilizing market observable inputs to determine their fair value. Our marketable equity securities are publicly traded stocks measured at fair value and classified within Level 1 in the fair value hierarchy because we use quoted prices for identical assets in active markets to estimate their fair value. 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	September 30, 2023		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash	$	5,333
Cash equivalents:
Money market funds	29,639		$	29,639	$	—	$	—
U.S. government and agency securities	1,445		1,445		—		—

Time deposits	350		—		350		—
Corporate debt securities	123		—		123		—
Total cash and cash equivalents	36,890		31,084		473		—
Marketable securities:
U.S. government securities	8,741		8,741		—		—
U.S. government agency securities	4,028		4,028		—		—
Corporate debt securities	11,464		—		11,464		—

Total marketable securities	24,233		12,769		11,464		—
Restricted cash equivalents	836		836		—		—
Other assets	96		—		—		96
Total	$	62,055	$	44,689	$	11,937	$	96


			Fair Value Measurement at Reporting Date Using
Description	December 31, 2022		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash	$	6,176
Cash equivalents:
Money market funds	8,305		$	8,305	$	—	$	—
U.S. government and agency securities	16		16		—		—

Time deposits	156		—		156		—
Corporate debt securities	28		—		28		—
Total cash and cash equivalents	14,681		8,321		184		—
Marketable securities:
U.S. government securities	8,708		8,708		—		—
U.S. government agency securities	4,989		4,989		—		—
Corporate debt securities	12,335		—		12,335		—
Marketable equity securities	25		25		—		—
Total marketable securities	26,057		13,722		12,335		—
Restricted cash equivalents	583		583		—		—
Other assets	157		—		—		157
Total	$	41,478	$	22,626	$	12,519	$	157

The following tables summarize our available-for-sale marketable debt securities with unrealized losses as of September 30, 2023 and December 31, 2022, aggregated by major security type and the length of time that individual securities have been in a continuous loss position (in millions):


	September 30, 2023
	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	$	567	$	(7)	$	7,235	$	(424)	$	7,802	$	(431)
U.S. government agency securities	252		(1)		3,673		(230)		3,925		(231)
Corporate debt securities	660		(10)		10,196		(715)		10,856		(725)
Total	$	1,479	$	(18)	$	21,104	$	(1,369)	$	22,583	$	(1,387)


	December 31, 2022
	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	$	5,008	$	(234)	$	3,499	$	(247)	$	8,507	$	(481)
U.S. government agency securities	524		(17)		4,415		(308)		4,939		(325)
Corporate debt securities	4,555		(249)		7,256		(634)		11,811		(883)
Total	$	10,087	$	(500)	$	15,170	$	(1,189)	$	25,257	$	(1,689)

The decrease in the gross unrealized losses for the nine months ended September 30, 2023 is due to a shorter average portfolio duration. The allowance for credit losses and the gross unrealized gains on our marketable debt securities were not material as of September 30, 2023 and December 31, 2022.

Our non-marketable equity securities accounted for using the measurement alternative are measured at fair value on a non-recurring basis and are classified within Level 3 of the fair value hierarchy because we use significant unobservable inputs to estimate their fair value. Assets remeasured at fair value on a non-recurring basis within Level 3 during the nine months ended September 30, 2023 and 2022 were $53 million and $182 million, respectively. For additional information, see Note 6 — Non-marketable Equity Securities.