Short-term Investments

6 Months Ended

Jun. 30, 2021

Investments, Debt and Equity Securities [Abstract]

Short-term investments consisted of available-for-sale and equity securities as follows (in thousands):


Type of securities as of June 30, 2021	Amortized cost		Gross unrealized gains		Gross unrealized losses		Fair value
Corporate debt securities	$	182,739	$	7	$	(51)	$	182,695
Government-related debt securities	28,104		—		(18)		28,086
Asset-backed securities	26,857		3		(3)		26,857
Total available-for-sale debt securities	$	237,700	$	10	$	(72)	$	237,638


Type of securities as of December 31, 2020	Amortized cost		Gross unrealized gains		Gross unrealized losses		Fair value
Corporate debt securities	$	22,338	$	71	$	—	$	22,409
Government-related debt securities	5,000		3		—		5,003
Asset-backed securities	1,462		9		—		1,471
Total available-for-sale debt securities	$	28,800	$	83	$	—	$	28,883

The fair values of available-for-sale debt securities by contractual maturity were as follows (in thousands):


	June 30, 2021		December 31, 2020
Maturing in one year or less	$	159,596	$	28,883
Maturing in one to three years	78,042		—
Total available-for-sale debt securities	$	237,638	$	28,883

The Company has both the intent and ability to sell its available-for-sale debt securities maturing greater than one year within 12 months from the balance sheet date and, accordingly, has classified these securities as current in the condensed consolidated balance sheets.

The following table summarizes investments that have been in a continuous unrealized loss position as of June 30, 2021 (in thousands).


	Less than 12 months				12 months or greater				Total
	Fair Value		Gross unrealized losses		Fair Value		Gross unrealized losses		Fair Value		Gross unrealized losses
Corporate debt securities	$	45,709	$	(51)	$	—	$	—	$	45,709	$	(51)
Government-related debt securities	23,021		(18)		—		—		23,021		(18)
Asset Backed Securities	11,260		(3)		—		—		11,260		(3)
Total	$	79,990	$	(72)	$	—	$	—	$	79,990	$	(72)

The Company invests in securities that are rated investment grade or better. The unrealized losses on available-for-sale debt securities as of June 30, 2021 were primarily caused by interest rate increases.

The Company reviews the individual securities in its portfolio for impairment when events indicate the fair value of the investments may be below the carrying value. The Company reviews the individual securities in its portfolio for indications that unrealized losses are credit related and require an allowance to be recorded at the present value of the future expected cash flows. The Company determined unrealized losses were not for credit losses and so did not record an allowance related to its available-for-sale debt investments for the three and six month periods ended June 30, 2021. The Company did not record any impairment charges related to its available-for-sale debt investments for the three and six month periods ended June 30, 2021.