Marketable Securities

12 Months Ended

Dec. 31, 2022

Investments, Debt and Equity Securities [Abstract]

3. Marketable securities

Marketable securities by security type consisted of the following:


	December 31, 2022
(in thousands)	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. treasury bills and notes	$	228,432	$	13	$	(301	)	$	228,144
U.S. agency securities		211,658		68		(474	)		211,252
Total	$	440,090	$	81	$	(775	)	$	439,396


	December 31, 2021
(in thousands)	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. treasury bills and notes	$	277,559	$	—	$	(218	)	$	277,341
U.S. agency securities		18,781		—		(10	)		18,771
Total	$	296,340	$	—	$	(228	)	$	296,112

The remaining contractual maturities of all marketable securities were less than 18 months as of December 31, 2022 and 2021.The unrealized losses on the Company’s marketable securities of $0.8 million and $0.2 million as of December 31, 2022 and 2021, respectively, were caused by interest rate increases which resulted in the decrease in market value of these securities. Because the decline in fair value is attributable to changes in interest rates and not credit quality, and because the Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases, which may be maturity, the Company does not consider those marketable securities to be

other-than-temporarily impaired at December 31, 2022 or 2021. None of the Company’s marketable securities have been in a continuous unrealized loss position for 12 months or greater as of December 31, 2022 or 2021.