The following table summarizes our assets measured at fair value and the classification by level of input within the fair value hierarchy (in millions):


			Fair Value Measurement at Reporting Date Using
Description	December 31, 2021		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Cash equivalents:
Money market funds	$	8,850	$	8,850	$	—
U.S. government securities	25		25		—
U.S. government agency securities	108		108		—
Certificates of deposit and time deposits	250		—		250
Corporate debt securities	60		—		60
Marketable securities:
U.S. government securities	10,901		10,901		—
U.S. government agency securities	5,927		5,927		—
Corporate debt securities	14,569		—		14,569
Total cash equivalents and marketable securities	$	40,690	$	25,811	$	14,879


			Fair Value Measurement at Reporting Date Using
Description	December 31, 2020		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Cash equivalents:
Money market funds	$	9,755	$	9,755	$	—
U.S. government securities	1,016		1,016		—

Certificates of deposit and time deposits	305		—		305
Corporate debt securities	12		—		12
Marketable securities:
U.S. government securities	20,921		20,921		—
U.S. government agency securities	11,698		11,698		—
Corporate debt securities	11,759		—		11,759
Total cash equivalents and marketable securities	$	55,466	$	43,390	$	12,076