Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Summary of Investments Measured at Fair Value on Recurring Basis

The following table summarizes the Company’s investments at September 30, 2023 and December 31, 2022 measured at fair value on a recurring basis (in thousands):

	September 30, 2023							December 31, 2022
			Gross							Gross
			Unrealized			Recorded				Unrealized			Recorded
	Cost		Losses			Basis		Cost		Losses			Basis
Current:
Cash equivalents:
U.S. treasuries	$	8,398	$	-		$	8,398	$	-	$	-		$	-
Money market funds		1,502		-			1,502		40,296		-			40,296
Total cash equivalents		9,900		-			9,900		40,296		-			40,296
Investments:
Corporate bonds		38,525		(5,088	)		33,437		38,489		(5,181	)		33,308
U.S. treasuries		16,690		(1,683	)		15,007		-		-			-
Asset backed securities		13,672		(341	)		13,331		13,709		(737	)		12,972
U.S. government agency securities		12,853		(635	)		12,218		7,369		(302	)		7,067
Mortgage backed securities		15,351		(3,676	)		11,675		16,135		(3,139	)		12,996
Emerging markets		2,014		(29	)		1,985		2,044		(62	)		1,982
Total current investments		99,105		(11,452	)		87,653		77,746		(9,421	)		68,325
Restricted cash and investments (1):
U.S. treasuries		83,064		(8,532	)		74,532		66,479		(9,222	)		57,257
Corporate bonds		82,708		(11,823	)		70,885		81,993		(11,296	)		70,697
Mortgage backed securities		43,389		(7,574	)		35,815		46,138		(6,045	)		40,093
U.S. government agency securities		16,872		(1,629	)		15,243		26,479		(2,156	)		24,323
Mutual funds		7,857		-			7,857		6,301		-			6,301
Asset backed securities		799		(9	)		790		9		-			9
Money market funds		173		-			173		646		-			646
Total restricted cash and    investments		234,862		(29,567	)		205,295		228,045		(28,719	)		199,326
Total investments	$	343,867	$	(41,019	)	$	302,848	$	346,087	$	(38,140	)	$	307,947

(1) Included in restricted cash and investments within the condensed consolidated balance sheets is restricted cash of $2.1 million and $15.9 million as of September 30, 2023 and December 31, 2022, 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, 2023 and December 31, 2022 measured at fair value on a recurring basis by fair value hierarchy level (in thousands):

	September 30, 2023								December 31, 2022
	Total								Total
	Recorded								Recorded
	Basis		Level 1		Level 2		Other (1)		Basis		Level 1		Level 2		Other (1)
Cash equivalents:
U.S. treasuries	$	8,398	$	-	$	8,398	$	-	$	-	$	-	$	-	$	-
Money market    funds		1,502		-		-		1,502		40,296		-		-		40,296
Investments:
Corporate bonds		33,437		-		33,437		-		33,308		-		33,308		-
U.S. treasuries		15,007		-		15,007		-		-		-		-		-
Asset backed securities		13,331		-		13,331		-		12,972		-		12,972		-
U.S. government    agency securities		12,218		-		12,218		-		7,067		-		7,067		-
Mortgage backed    securities		11,675		-		11,675		-		12,996		-		12,996		-
Emerging markets		1,985		-		1,985		-		1,982		-		1,982		-
Restricted cash and    investments:
U.S. treasuries		74,532		-		74,532		-		57,257		-		57,257		-
Corporate bonds		70,885		-		70,885		-		70,697		-		70,697		-
Mortgage backed    securities		35,815		-		35,815		-		40,093		-		40,093		-
U.S. government    agency securities		15,243		-		15,243		-		24,323		-		24,323		-
Mutual funds		7,857		7,857		-		-		6,301		6,301		-		-
Asset backed securities		790		-		790		-		9		-		9		-
Money market    funds		173		-		-		173		646		-		-		646
Total investments	$	302,848	$	7,857	$	293,316	$	1,675	$	307,947	$	6,301	$	260,704	$	40,942

(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, 2023 and December 31, 2022. Actual maturities may differ from contractual maturities because borrowers may have the right to prepay obligations with or without prepayment penalties. The table also includes money market funds, which are classified as cash and cash equivalents on the Company’s consolidated balance sheets.

	September 30, 2023
(In thousands)	Less than 1 Year		Between 1 to 5 Years		Between 5 to 10 Years		After 10 Years		Total
Corporate bonds	$	3,209	$	65,749	$	35,197	$	167	$	104,322
U.S. treasuries		42,587		26,839		28,511		-		97,937
U.S. government agency securities		38		25,448		1,975		-		27,461
Asset backed securities		-		790		12,073		1,258		14,121
Emerging markets		1,985		-		-		-		1,985
Money market funds		1,675		-		-		-		1,675
Total	$	49,494	$	118,826	$	77,756	$	1,425	$	247,501
	December 31, 2022
(In thousands)	Less than 1 Year		Between 1 to 5 Years		Between 5 to 10 Years		After 10 Years		Total
Corporate bonds	$	646	$	50,439	$	52,920	$	-	$	104,005
U.S. treasuries		440		3,405		53,412		-		57,257
Money market funds		40,539		-		-		-		40,539
U.S. government agency securities		3,943		24,025		3,422		-		31,390
Asset backed securities		-		9		2,113		10,859		12,981
Emerging markets		-		1,982		-		-		1,982
Total	$	45,568	$	79,860	$	111,867	$	10,859	$	248,154