Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table presents our fair value hierarchy for our assets measured at fair value on a recurring basis as of December 31, 2019 (in thousands): 

	Level 1		Level 2		Total
Cash equivalents:
Money market funds	$	486,982	$	—	$	486,982
Commercial paper	—		86,388		86,388
Marketable securities:
Commercial paper	—		101,490		101,490
Corporate notes and bonds	—		1,661,330		1,661,330
Certificates of deposit	—		38,045		38,045
U.S. government and agency securities	—		127,784		127,784
Total	$	486,982	$	2,015,037	$	2,502,019

The following table presents our fair value hierarchy for our assets measured at fair value on a recurring basis as of December 31, 2018 (in thousands): 

	Level 1		Level 2		Total
Cash equivalents:
Money market funds	$	229,047	$	—	$	229,047
Commercial paper	—		16,961		16,961
Certificates of deposit	—		2,465		2,465
Marketable securities:
Commercial paper	—		108,061		108,061
Corporate notes and bonds	—		1,229,714		1,229,714
Certificates of deposit	—		73,585		73,585
U.S. government and agency securities	—		102,214		102,214
Total	$	229,047	$	1,533,000	$	1,762,047