Fair Value Measurement (Tables)

6 Months Ended

Jun. 30, 2021

Summary of Investments Measured at Fair Value on Recurring Basis

The following table summarizes the Company’s investments at June 30, 2021 and December 31, 2020 measured at fair value on a recurring basis (in thousands):

	June 30, 2021							December 31, 2020
			Gross							Gross
			Unrealized							Unrealized
			Gains			Recorded				Gains			Recorded
	Cost		(Losses)			Basis		Cost		(Losses)			Basis
Current:
Cash equivalents:
Money market funds	$	1,149	$	—		$	1,149	$	42,007	$	—		$	42,007
Total cash equivalents		1,149		—			1,149		42,007		—			42,007
Investments:
Corporate bonds		48,243		541			48,784		50,918		884			51,802
Asset backed securities		36,943		(7	)		36,936		36,948		(146	)		36,802
Mortgage backed securities		11,592		(125	)		11,467		4,367		24			4,391
U.S. government agency securities		7,389		593			7,982		7,396		752			8,148
U.S. treasuries		2,101		14			2,115		100		1			101
Total current investments		106,268		1,016			107,284		99,729		1,515			101,244
Restricted cash and investments ⁽¹⁾:
Corporate bonds		183,186		1,628			184,814		88,902		4,091			92,993
Mortgage backed securities		88,288		1,470			89,758		48,795		2,356			51,151
U.S. treasuries		69,225		147			69,372		4,371		19			4,390
U.S. government agency securities		34,908		1,909			36,817		29,737		2,466			32,203
Mutual funds		6,121		—			6,121		5,036		—			5,036
Money market funds		396		—			396		40,063		(4	)		40,059
Asset backed securities		203		2			205		256		4			260
Supranational bonds		—		—			—		4,775		3			4,778
Total restricted cash and investments		382,327		5,156			387,483		221,935		8,935			230,870
Total investments	$	489,744	$	6,172		$	495,916	$	363,671	$	10,450		$	374,121

(1) Included in restricted cash and investments within the condensed consolidated balance sheets is restricted cash of $11.5 million and $124.3 million as of June 30, 2021 and December 31, 2020, respectively, which is excluded from the table above. Restricted cash and investments are classified as current and noncurrent on the balance sheet based on the nature of the restriction.

Summary of Assets Measured at Fair Value on Recurring Basis

The following table summarizes the Company’s investments at June 30, 2021 and December 31, 2020 measured at fair value on a recurring basis by fair value hierarchy level (in thousands):

	June 30, 2021										December 31, 2020
	Total										Total
	Recorded										Recorded
	Basis		Level 1		Level 2		Level 3		Other ⁽¹⁾		Basis		Level 1		Level 2		Level 3		Other ⁽¹⁾
Cash equivalents:
Money market funds	$	1,149	$	—	$	—	$	—	$	1,149	$	42,007	$	—	$	—	$	—	$	42,007
Investments:
Corporate bonds		48,784		—		48,784		—		—		51,802		—		51,802		—		—
Asset backed securities		36,936		—		36,936		—		—		36,802		—		36,802		—		—
Mortgage backed securities		11,467		—		11,467		—		—		4,391		—		4,391		—		—
U.S. government agency securities		7,982		—		7,982		—		—		8,148		—		8,148		—		—
U.S. treasuries		2,115		—		2,115		—		—		101		—		101		—		—
Restricted cash and investments:
Corporate bonds		184,814		—		184,814		—		—		92,993		—		92,993		—		—
Mortgage backed securities		89,758		—		89,758		—		—		51,151		—		51,151		—		—
U.S. treasuries		69,372		—		69,372		—		—		4,390		—		4,390		—		—
U.S. government agency securities		36,817		—		36,817		—		—		32,203		—		32,203		—		—
Mutual funds		6,121		6,121		—		—		—		5,036		5,036		—		—		—
Money market funds		396		—		—		—		396		40,059		—		—		—		40,059
Asset backed securities		205		—		205		—		—		260		—		260		—		—
Supranational bonds		—		—		—		—		—		4,778		—		4,778		—		—
Total investments	$	495,916	$	6,121	$	488,250	$	—	$	1,545	$	374,121	$	5,036	$	287,019	$	—	$	82,066

(1) Investments in money market funds measured at fair value using the net asset value per share practical expedient are not subject to hierarchy level classification disclosure. The Company invests in money market funds that seek to maintain a stable net asset value. These investments include commingled funds that comprise high-quality short-term securities representing liquid debt and monetary instruments where the redemption value is likely to be the fair value. Redemption is permitted daily without written notice.

Summary of Contractual Maturities of Available for Sale Securities

The following table summarizes the contractual maturities of the Company’s available-for-sale securities at June 30, 2021 and December 31, 2020. Actual maturities may differ from contractual maturities because borrowers may have the right to prepay obligations with or without prepayment penalties.

	June 30, 2021
(In thousands)	Less than 1 Year		Between 1 to 5 Years		Between 5 to 10 Years		After 10 Years		Total
Corporate bonds	$	24,506	$	67,063	$	142,029	$	—	$	233,598
U.S. treasuries		1,010		424		70,053		—		71,487
U.S. government agency securities		1,002		18,413		25,384		—		44,799
Asset backed securities		—		209		2,201		34,731		37,141
Money market funds	$	1,545	$	—	$	—	$	—	$	1,545
Total	$	28,063	$	86,109	$	239,667	$	34,731	$	388,570

	December 31, 2020
(In thousands)	Less than 1 Year		Between 1 to 5 Years		Between 5 to 10 Years		After 10 Years		Total
Corporate bonds	$	49,308	$	61,315	$	34,172	$	—	$	144,795
Money market funds		82,066		—		—		—		82,066
U.S. government agency securities		1,013		18,668		20,670		—		40,351
Asset backed securities		2		267		—		36,793		37,062
Supranational bonds		4,778		—		—		—		4,778
U.S. treasuries		1,367		1,504		1,620		—		4,491
Total	$	138,534	$	81,754	$	56,462	$	36,793	$	313,543