Marketable Securities

3 Months Ended

Mar. 31, 2021

Investments, Debt and Equity Securities [Abstract]

Marketable securities

Marketable securities

The following table summarizes the marketable securities held at March 31, 2021 and December 31, 2020 (in thousands):

Description	Amortized cost / Cost		Unrealized gains		Unrealized losses		Fair value
March 31, 2021
U.S. government agency securities and treasuries	$	429,039	$	256	$	(16)	$	429,279
Corporate bonds	142,773		163		(40)		142,896
Commercial paper	78,955		—		—		78,955
Equity securities	4,305		—		(1,598)		2,707
Total	$	655,072	$	419	$	(1,654)	$	653,837
December 31, 2020
U.S. government agency securities and treasuries	$	675,043	$	302	$	(74)	$	675,271
Corporate bonds	197,171		432		(40)		197,563
Commercial paper	77,949		1		—		77,950
Equity securities	20,017		—		(14,364)		5,653
Total	$	970,180	$	735	$	(14,478)	$	956,437

No available-for-sale debt securities held as of March 31, 2021 or December 31, 2020 had remaining maturities greater than five years.