Marketable securities (Tables)

12 Months Ended

Dec. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Summary of Marketable Securities Held

The following table summarizes the marketable securities held at December 31, 2020 and 2019 (in thousands):

	Amortized cost / cost		Unrealized gains		Unrealized losses		Fair value
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
December 31, 2019
U.S. government agency securities and treasuries	$	633,970	$	2,014	$	(48)	$	635,936
Certificates of deposit	960		—		—		960
Corporate bonds	185,827		824		(43)		186,608
Commercial paper	74,378		—		—		74,378
Equity securities	20,017		—		(7,147)		12,870
Total	$	915,152	$	2,838	$	(7,238)	$	910,752