Marketable Securities

12 Months Ended

Dec. 31, 2023

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 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


As of December 31, 2022	Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
U.S. Treasury securities	1 or less	$	230,349	$	1	$	(2,283)	$	228,067
U.S. Government agency securities	1 or less	5,000		—		(34)		4,966
Negotiable certificates of deposit	1 or less	3,911		1		(57)		3,855
Corporate debt securities	1 or less	16,360		—		(286)		16,074
U.S. Treasury securities	1 - 2	16,919		—		(41)		16,878
Negotiable certificates of deposit	1 - 2	490		1		—		491

Total		$	273,029	$	3	$	(2,701)	$	270,331

The unrealized losses on the Company’s marketable securities were caused by interest rate increases and resulted in the decrease in market value of these securities. There were no allowances for credit losses at December 31, 2023 and 2022 because (i) the decline in fair value is attributable to changes in interest rates and not credit quality, (ii) the Company does not intend to sell the investments before maturity, and (iii) 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.

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 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


	Less Than 12 Months				12 Months or Greater				Total
As of December 31, 2022	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. Treasury securities	$	178,568	$	1,056	$	61,377	$	1,267	$	239,945	$	2,323
U.S. Government agency securities	4,966		34		—		—		4,966		34
Corporate debt securities	2,228		21		13,846		265		16,074		286
Negotiable certificates of deposit	726		9		1,903		48		2,629		57
Total	$	186,488	$	1,120	$	77,126	$	1,580	$	263,614	$	2,700

Accrued interest receivable on available-for-sale securities was $2.6 million and $1.3 million at December 31, 2023 and 2022, respectively. We have not written off any accrued interest receivable in any of the periods presented in these financial statements.