Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2024

Investments, Debt and Equity Securities [Abstract]

The Company’s marketable securities, which consist of highly liquid marketable debt securities, are classified as available-for-sale and are stated at fair value. The following tables summarize the Company’s marketable securities (in thousands):


As of March 31, 2024	Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
U.S. Treasury securities	1 or less	$	389,180	$	26	$	(518)	$	388,688

Negotiable certificates of deposit	1 or less	4,165		—		(7)		4,158

U.S. Treasury securities	1 - 2	51,592		69		(34)		51,627


Total		$	444,937	$	95	$	(559)	$	444,473


As of December 31, 2023	Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
U.S. Treasury securities	1 or less	$	301,053	$	102	$	(530)	$	300,625
U.S. Government agency securities	1 or less	5,000		—		(2)		4,998
Negotiable certificates of deposit	1 or less	4,410		1		(4)		4,407

U.S. Treasury securities	1 - 2	98,701		600		(36)		99,265
Negotiable certificates of deposit	1 - 2	980		—		(6)		974
Total		$	410,144	$	703	$	(578)	$	410,269

Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value

The following table summarizes marketable securities in a continuous unrealized loss position for which an allowance for credit losses was not recorded (in thousands):


	Less Than 12 Months				12 Months or Greater				Total
As of March 31, 2024	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. Treasury securities	$	332,907	$	552	$	—	$	—	$	332,907	$	552

Negotiable certificates of deposit	2,204		1		1,955		6		4,159		7
Total	$	335,111	$	553	$	1,955	$	6	$	337,066	$	559


	Less Than 12 Months				12 Months or Greater				Total
As of December 31, 2023	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. Treasury securities	$	214,291	$	566	$	—	$	—	$	214,291	$	566
U.S. Government agency securities	4,998		2		—		—		4,998		2
Negotiable certificates of deposit	3,665		10		—		—		3,665		10
Total	$	222,954	$	578	$	—	$	—	$	222,954	$	578