Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of Financial Instruments (Excluding Restricted Cash) Measured at Fair Value on Recurring Basis

The following tables set forth the Company’s financial instruments (excluding restricted cash) that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):

	December 31, 2020
	Total		Level 1		Level 2		Level 3
Money market funds	$	146,468	$	146,468	$	-	$	-
U.S. treasury securities		301,112		-		301,112		-
U.S. government agency obligations		25,001		-		25,001		-
Corporate securities and commercial paper		262,505		-		262,505		-
Total assets measured at fair value	$	735,086	$	146,468	$	588,618	$	-

	December 31, 2019
	Total		Level 1		Level 2		Level 3
Money market funds	$	45,498	$	45,498	$	-	$	-
U.S. treasury securities		74,854		-		74,854		-
Corporate securities and commercial paper		67,918		-		67,918		-
Total assets measured at fair value	$	188,270	$	45,498	$	142,772	$	-

Schedule of Investments Classified as Available for Sale Securities with Contractual Maturities

Classified as (with contractual maturities):

	Year Ended December 31,
	2020		2019
Cash and cash equivalents	$	173,415	$	57,937
Short-term investments (due within one year)		555,231		130,333
Long-term investments (due between one and two    years)		6,440		-
	$	735,086	$	188,270

Schedule of Fair Value and Amortized Cost of Investments in Marketable Securities by Major Security Type

The fair value and amortized cost of investments in marketable securities by major security type as of December 31, 2020 and 2019 are presented in the tables that follow (in thousands):

	Amortized Cost		Unrealized Gain		Unrealized Loss			Fair Value
As of December 31, 2020:
Money market funds	$	146,468	$	-	$	-		$	146,468
U.S. treasury securities		301,075		38		(1	)		301,112
U.S. government agency obligations		24,997		4		-			25,001
Corporate securities and commercial paper		262,502		15		(12	)		262,505
Total	$	735,042	$	57	$	(13	)	$	735,086

	Amortized Cost		Unrealized Gain		Unrealized Loss			Fair Value
As of December 31, 2019:
Money market funds	$	45,498	$	-	$	-		$	45,498
U.S. treasury securities		74,801		12		(1	)		74,812
Corporate securities and commercial paper		67,907		55		(2	)		67,960
Total	$	188,206	$	67	$	(3	)	$	188,270