Marketable Securities

3 Months Ended

Mar. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable Securities

The amortized cost, gross unrealized holding gains, gross unrealized holding losses and fair value of debt securities available-for-sale by type of security at March 31, 2022 and December 31, 2021 was as follows:

	Amortized Cost		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
March 31, 2022
Corporate bonds
U.S.	$	290,201	$	—	$	290,201	$	2	$	(1,969)	$	288,234
Foreign	47,106		—		47,106		—		(426)		46,680
Government related obligations
U.S.	98,707		—		98,707		1		(212)		98,496
Total	$	436,014	$	—	$	436,014	$	3	$	(2,607)	$	433,410
December 31, 2021
Corporate bonds
U.S.	$	130,388	$	—	$	130,388	$	1	$	(234)	$	130,155
Foreign	20,643		—		20,643		—		(82)		20,561
Government related obligations
U.S.	41,939		—		41,939		—		(8)		41,931
Total	$	192,971	$	—	$	192,971	$	1	$	(324)	$	192,648

The Company had 99 and 53 available-for-sale debt securities in an unrealized loss position, with an aggregate fair value of $412,366 and $185,296, as of March 31, 2022 and December 31, 2021, respectively. As of March 31, 2022, the Company did not intend to sell these securities, and did not believe it was more likely than not that it would be required to sell these securities prior to the anticipated recovery of their amortized cost basis. We did not have any investments in a continuous unrealized loss position for more than twelve months as of March 31, 2022 and December 31, 2021.

The net amortized cost and fair value of debt securities available-for-sale at March 31, 2022 and December 31, 2021 are shown below by contractual maturity. Actual maturities may differ from contractual maturities because securities may be restructured, called or prepaid, or the Company intends to sell a security prior to maturity. The fair values of available for sale debt securities are classified as marketable securities in the condensed consolidated balance sheets at March 31, 2022 and December 31, 2021.

	March 31, 2022				December 31, 2021
	Net Amortized Cost		Fair Value		Net Amortized Cost		Fair Value
Due to mature:
Less than one year	$	342,502	$	341,069	$	155,359	$	155,226
One year through five years	93,512		92,341		37,612		37,422
Total	$	436,014	$	433,410	$	192,971	$	192,648

Net Investment Income

Sources of net investment income included in other income (expense) in the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2022 and 2021 were as follows:

	Three Months Ended March 31,
	2022		2021
Gross investment income from debt securities available-for-sale	$	140	$	72
Investment expenses	(18)		(52)
Net investment income (excluding net realized capital gains or losses)	122		20
Net realized capital (losses) gains	(3)		19
Net investment income	$	119	$	39

We utilize the specific identification method in computing realized gains and losses. The proceeds from the sale of available-for-sale debt securities and the related gross realized capital gains and losses for the three months ended March 31, 2022 and 2021 were the following:

	Three Months Ended March 31,
	2022		2021
Proceeds from sales	$	—	$	113,441
Gross realized capital gains	—		19
Gross realized capital losses	$	—	—