Marketable Securities and Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Marketable Securities

As of December 31, 2019, marketable securities by security type consisted of:

(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Commercial paper (due within one year)	$	314,292	$	74	$	(23)	$	314,343
U.S. Government securities (due within one year)	78,612		48		(3)		78,657
Certificates of deposit (due within one year)	66,241		17		(2)		66,256
Total	$	459,145	$	139	$	(28)	$	459,256

Schedule of Financial Assets Measured at Fair Value on a Recurring Basis

The following tables present information about the Company's financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values:

As of December 31, 2019 (in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	—	$	28,192	$	—	$	28,192
Certificates of deposit	—		20,500		—		20,500
Marketable securities:
Commercial paper	—		314,343		—		314,343
U.S. Government securities	—		78,657		—		78,657
Certificates of deposit	—		66,256		—		66,256
Total	$	—	$	507,948	$	—	$	507,948

As of December 31, 2018 (in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	—	$	267,145	$	—	$	267,145
Total	$	—	$	267,145	$	—	$	267,145