Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2021

Summary of Investments Measured at Fair Value on Recurring Basis

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

	September 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	$	10,742	$	—		$	10,742	$	42,007	$	—		$	42,007
Total cash equivalents		10,742		—			10,742		42,007		—			42,007
Investments:
Corporate bonds		42,007		344			42,351		50,918		884			51,802
Asset backed securities		33,548		(25	)		33,523		36,948		(146	)		36,802
Mortgage backed securities		19,197		(296	)		18,901		4,367		24			4,391
U.S. government agency securities		7,386		548			7,934		7,396		752			8,148
U.S. treasuries		—		—			—		100		1			101
Total current investments		102,138		571			102,709		99,729		1,515			101,244
Restricted cash and investments ⁽¹⁾:
Corporate bonds		127,026		1,209			128,235		88,902		4,091			92,993
Mortgage backed securities		71,546		1,331			72,877		48,795		2,356			51,151
U.S. treasuries		67,908		(32	)		67,876		4,371		19			4,390
U.S. government agency securities		32,928		1,703			34,631		29,737		2,466			32,203
Mutual funds		6,104		—			6,104		5,036		—			5,036
Asset backed securities		150		1			151		256		4			260
Money market funds		143		—			143		40,063		(4	)		40,059
Supranational bonds		—		—			—		4,775		3			4,778
Total restricted cash and investments		305,805		4,212			310,017		221,935		8,935			230,870
Total investments	$	418,685	$	4,783		$	423,468	$	363,671	$	10,450		$	374,121

(1) Included in restricted cash and investments within the condensed consolidated balance sheets is restricted cash of $9.4 million and $124.3 million as of September 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 September 30, 2021 and December 31, 2020 measured at fair value on a recurring basis by fair value hierarchy level (in thousands):

	September 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	$	10,742	$	—	$	—	$	—	$	10,742	$	42,007	$	—	$	—	$	—	$	42,007
Investments:
Corporate bonds		42,351		—		42,351		—		—		51,802		—		51,802		—		—
Asset backed securities		33,523		—		33,523		—		—		36,802		—		36,802		—		—
Mortgage backed securities		18,901		—		18,901		—		—		4,391		—		4,391		—		—
U.S. government agency securities		7,934		—		7,934		—		—		8,148		—		8,148		—		—
U.S. treasuries		—		—		—		—		—		101		—		101		—		—
Restricted cash and investments:
Corporate bonds		128,235		—		128,235		—		—		92,993		—		92,993		—		—
Mortgage backed securities		72,877		—		72,877		—		—		51,151		—		51,151		—		—
U.S. treasuries		67,876		—		67,876		—		—		4,390		—		4,390		—		—
U.S. government agency securities		34,631		—		34,631		—		—		32,203		—		32,203		—		—
Mutual funds		6,104		6,104		—		—		—		5,036		5,036		—		—		—
Asset backed securities		151		—		151		—		—		260		—		260		—		—
Money market funds		143		—		—		—		143		40,059		—		—		—		40,059
Supranational bonds		—		—		—		—		—		4,778		—		4,778		—		—
Total investments	$	423,468	$	6,104	$	406,479	$	—	$	10,885	$	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 September 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.

	September 30, 2021
(In thousands)	Less than 1 Year		Between 1 to 5 Years		Between 5 to 10 Years		After 10 Years		Total
Corporate bonds	$	22,114	$	48,127	$	100,345	$	—	$	170,586
U.S. treasuries		1,005		1,987		64,884		—		67,876
U.S. government agency securities		—		23,742		18,823		—		42,565
Asset backed securities		—		153		2,200		31,321		33,674
Money market funds	$	10,885	$	—	$	—	$	—	$	10,885
Total	$	34,004	$	74,009	$	186,252	$	31,321	$	325,586

	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