Marketable Securities

6 Months Ended

Jun. 30, 2021

Investments, Debt and Equity Securities [Abstract]

Marketable securities

Marketable securities

The following table summarizes the marketable securities held at June 30, 2021 and December 31, 2020 (in thousands):

Description	Amortized cost / Cost		Unrealized gains		Unrealized losses		Fair value
June 30, 2021
U.S. government agency securities and treasuries	$	346,331	$	138	$	(13)	$	346,456
Corporate bonds	136,133		41		(27)		136,147
Commercial paper	102,937		—		—		102,937
Equity securities	4,305		—		(1,685)		2,620
Total	$	589,706	$	179	$	(1,725)	$	588,160
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 June 30, 2021 or December 31, 2020 had remaining maturities greater than five years.