Cash, Cash Equivalents, and Investments (Tables)

12 Months Ended

Dec. 31, 2021

Dec. 31, 2020

Cash and Cash Equivalents [Abstract]

Components of Cash, Cash Equivalents and Investments

Cash, cash equivalents, and investments consisted of the following (in thousands):

	December 31,
	2021		2020
Cash	$	185,624	$	266,609
Money market instruments	537		2,464
Cash and cash equivalents	186,161		269,073
Corporate bonds	73,088		32,714
Asset-backed securities	37,655		25,160
Treasury bills	18,912		35,403
Municipal bonds	4,998		1,303
Agency bonds	2,802		—
Sovereign bonds	—		8,660
Current investments	137,455		103,240
Corporate bonds	481,218		203,428
Asset-backed securities	43,940		67,058
Treasury bills	39,753		96,458
Agency bonds	16,077		19,006
Sovereign bonds	2,119		3,440
Municipal bonds	641		5,735
Non-current investments	583,748		395,125
	$	907,364	$	767,438

Summary of Available-for-Sale Investments

The following table summarizes the Company’s available-for-sale investments as of December 31, 2021 (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Current:
Corporate bonds	$	72,863	$	251	$	(26)	$	73,088
Asset-backed securities	37,568		112		(25)		37,655
Treasury bills	18,864		51		(3)		18,912
Municipal bonds	5,029		1		(32)		4,998
Agency bonds	2,800		2		—		2,802
Non-current:
Corporate bonds	485,140		555		(4,477)		481,218
Asset-backed securities	44,197		45		(302)		43,940
Treasury bills	39,740		46		(33)		39,753
Agency bonds	16,128		—		(51)		16,077
Sovereign bonds	2,141		—		(22)		2,119
Municipal bonds	635		6		—		641
	$	725,105	$	1,069	$	(4,971)	$	721,203

Gross Unrealized Losses and Fair Value for Available-for-Sale Investments

	Unrealized Loss Position For Less than 12 Months				Unrealized Loss Position For Greater than 12 Months				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Corporate bonds	$	431,652	$	(4,470)	$	3,110	$	(33)	$	434,762	$	(4,503)
Asset-backed securities	50,980		(317)		806		(10)		51,786		(327)
Treasury bills	25,040		(36)		—		—		25,040		(36)
Agency Bonds	16,077		(51)		—		—		16,077		(51)
Municipal bonds	—		—		3,892		(32)		3,892		(32)
Sovereign bonds	2,119		(22)		—		—		2,119		(22)
	$	525,868	$	(4,896)	$	7,808	$	(75)	$	533,676	$	(4,971)

Debt Securities, Available-for-sale, Allowance for Credit Loss

The following table summarizes changes in the allowance for credit losses (in thousands):

Balance as of December 31, 2019	$	—
Increases to the allowance for credit losses	160
Decreases to the allowance for credit losses	(160)
Balance as of December 31, 2020	—
Balance as of December 31, 2021	$	—

The following table summarizes changes in the allowance for credit losses (in thousands):

Balance as of December 31, 2019	$	—
Increases to the allowance for credit losses	160
Decreases to the allowance for credit losses	(160)
Balance as of December 31, 2020	—
Balance as of December 31, 2021	$	—

Effective Maturity Dates of Available-for-Sale Investments

The following table summarizes the effective maturity dates of the Company’s available-for-sale investments as of December 31, 2021 (in thousands):

	<1 Year		1-2 Years		2-3 Years		3-4 Years		4-5 Years		Total
Corporate bonds	$	73,088	$	205,331	$	175,992	$	64,356	$	35,539	$	554,306
Asset-backed securities	37,655		23,370		4,668		8,092		7,810		81,595
Treasury bills	18,912		39,753		—		—		—		58,665
Agency bonds	2,802		16,077		—		—		—		18,879
Municipal bonds	4,998		641		—		—		—		5,639
Sovereign bonds	—		—		1,052		1,067		—		2,119
	$	137,455	$	285,172	$	181,712	$	73,515	$	43,349	$	721,203