Investments (Tables)

12 Months Ended

Dec. 31, 2021

Investments, Debt and Equity Securities [Abstract]

Summary of debt securities available-for-sale

The following table summarizes our cash equivalents and available-for-sale debt investments:

	December 31, 2021
									Fair Value Level
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses (1)		Total Fair Value		Level 1		Level 2
	(In thousands)
Cash equivalents
Commercial paper	5,499		—		—		5,499		—		5,499
Corporate bonds	4,921		—		(5)		4,916		—		4,916
Money market funds	269,251		—		—		269,251		269,251		—
Municipal bonds	500		—		—		500		—		500
U.S. government bonds	4,000		—		—		4,000		4,000		—
Total cash equivalents (2)	284,171		—		(5)		284,166		273,251		10,915
Short-term investments
Asset-backed securities	12,915		1		(11)		12,905		—		12,905
Certificate of deposits	12,076		—		—		12,076		12,076		—
Commercial paper	30,691		—		—		30,691		—		30,691
Corporate bonds	179,235		1		(410)		178,826		—		178,826
Foreign government bonds	458		—		(1)		457		—		457
Municipal bonds	8,418		1		(2)		8,417		—		8,417
U.S. government bonds	2,966		—		(8)		2,958		2,958		—
Variable rate demand notes	500		—		—		500		—		500
Total short-term investments	247,259		3		(432)		246,830		15,034		231,796
Total	$	531,430	$	3	$	(437)	$	530,996	$	288,285	$	242,711

	December 31, 2020
									Fair Value Level
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses (1)		Total Fair Value		Level 1		Level 2
	(In thousands)
Cash equivalents
Certificate of deposits	$	976	$	—	$	—	$	976	$	976	$	—
Commercial paper	5,293		—		—		5,293		—		5,293
Corporate bonds	1,744		—		—		1,744		—		1,744
Money market funds	138,290		—		—		138,290		138,290		—
Municipal bonds	400		—		—		400		—		400
Total cash equivalents	146,703		—		—		146,703		139,266		7,437
Short-term investments
Asset-backed securities	19,111		18		(9)		19,120		—		19,120
Certificate of deposits	5,046		—		—		5,046		5,046		—
Commercial paper	15,148		—		—		15,148		—		15,148
Corporate bonds	50,771		16		(12)		50,775		—		50,775
Municipal bonds	12,702		8		(2)		12,708		—		12,708
U.S. government agency bonds	8,415		3		—		8,418		—		8,418
U.S. government bonds	17,605		3		—		17,608		17,608		—
Variable rate demand notes	300		—		—		300		—		300
Total short-term investments	129,098		48		(23)		129,123		22,654		106,469
Total	$	275,801	$	48	$	(23)	$	275,826	$	161,920	$	113,906

(1)All unrealized losses have been in a continuous loss position for less than 12 months. We do not intend to sell the investments in an unrealized loss position, and we do not believe it is more likely than not that we will be required to sell these investments before recovery of their amortized cost bases.

(2)During the years ended December 31, 2021 and 2020, we sold cash equivalent investments for proceeds of $12.8 million and $27.1 million, respectively, and realized no gain or loss on such sales.

The following table summarizes the contractual maturities of our cash equivalents and available-for-sale debt investments as of December 31, 2021:

	Amortized Cost		Fair Value
Within 1 year	$	489,384	$	489,057
After 1 year through 5 years	40,595		40,489
After 5 years through 10 years	123		123
After 10 years	$	1,328	$	1,327
Total	$	531,430	$	530,996

Actual maturities can differ from contractual maturities due to various factors including whether the issuers have the right to call or prepay obligations without call or prepayment penalties, and we view our available-for-sale debt investments as available for current operations.

As of December 31, 2021 and December 31, 2020, the amortized cost and fair market value of our held-to-maturity government bonds (Level 1) maturing within a year were $4.7 million.