Marketable Securities

3 Months Ended

Mar. 31, 2021

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 available-for-sale debt securities by type of security at March 31, 2021 was as follows:

	Amortized Cost		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Corporate bonds
U.S.	$	66,419	$	—	$	66,419	$	4	$	(29)	$	66,394
Foreign	35,171		—		35,171		—		(18)		35,153
Total	$	101,590	$	—	$	101,590	$	4	$	(47)	$	101,547

The amortized cost, gross unrealized holding gains, gross unrealized holding losses and fair value of available-for-sale debt securities by type of security at December 31, 2020 was as follows:

	Amortized Cost		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Corporate bonds
U.S.	$	185,989	$	—	$	185,989	$	1	$	(106)	$	185,884
Foreign	37,321		—		37,321		1		(21)		37,301
Total	$	223,310	$	—	$	223,310	$	2	$	(127)	$	223,185

The Company had 19 and 47 available-for-sale debt securities in an unrealized loss position, with an aggregate fair value of $98,515 and $212,378, as of March 31, 2021 and December 31, 2020, respectively. As of March 31, 2021, 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, 2021 and December 31, 2020.

The fair values of debt securities available-for-sale by classification in the condensed consolidated balance sheets were as follows:

	March 31, 2021		December 31, 2020
Marketable securities	$	101,547	$	223,185

The net amortized cost and fair value of debt securities available-for-sale at March 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.

	Net Amortized Cost		Fair Value
Due to mature:
Less than one year	$	101,590	$	101,547

Net Investment Income

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

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

The Company had no net investment income during the three months ended March 31, 2020.

We utilize the specific identification method in computing realized gains and losses. Realized gains and losses on our marketable securities were not material for the three months ended March 31, 2021. The Company had no maturities or sales of available-for-sale debt securities or resulting realized gains and losses for the three months ended March 31, 2020.