Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2019

Summary of Investments Measured at Fair Value on Recurring Basis

The following table summarizes the Company’s investments at March 31, 2019 and December 31, 2018 measured at fair value on a recurring basis (in thousands):

	March 31, 2019							December 31, 2018
			Gross							Gross
			Unrealized							Unrealized
			Gains			Recorded				Gains			Recorded
	Cost		(Losses)			Basis		Cost		(Losses)			Basis
Current:
Cash equivalents:
Money market funds	$	45	$	—		$	45	$	30	$	—		$	30
Total cash equivalents		45		—			45		30		—			30
Investments:
U.S. treasuries		499		—			499		347		—			347
U.S. government agency securities		50		—			50		50		(1	)		49
Corporate bonds		20		—			20		20		—			20
Total current investments		569		—			569		417		(1	)		416
Long term:
Investments:
U.S. treasuries		645		—			645		794		(3	)		791
Mortgage backed securities		469		(8	)		461		484		(13	)		471
Corporate bonds		422		1			423		422		(7	)		415
Asset backed securities		20		—			20		10		—			10
Total long term investments		1,556		(7	)		1,549		1,710		(23	)		1,687
Restricted cash and investments ⁽¹⁾:
Corporate bonds		178,726		(807	)		177,919		185,116		(3,739	)		181,377
Mortgage backed securities		82,648		(832	)		81,816		89,426		(2,026	)		87,400
U.S. government agency securities		43,076		(137	)		42,939		45,548		(908	)		44,640
U.S. treasuries		37,583		(168	)		37,415		44,304		(283	)		44,021
Money market funds		16,371		—			16,371		419		—			419
Supranational bonds		4,766		—			4,766		4,765		(24	)		4,741
Mutual funds		2,264		—			2,264		1,093		—			1,093
Asset backed securities		130		—			130		75		(1	)		74
Municipal bonds		50		—			50		50		—			50
Total restricted cash and investments		365,614		(1,944	)		363,670		370,796		(6,981	)		363,815
Total investments	$	367,784	$	(1,951	)	$	365,833	$	372,953	$	(7,005	)	$	365,948

(1) Included in restricted cash and investments within the condensed consolidated balance sheet as of March 31, 2019 is restricted cash of $134.2 million, 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 March 31, 2019 and December 31, 2018 measured at fair value on a recurring basis by fair value hierarchy level (in thousands):

	March 31, 2019								December 31, 2018
	Total								Total
	Recorded								Recorded
	Basis		Level 1		Level 2		Other ⁽¹⁾		Basis		Level 1		Level 2		Other ⁽¹⁾
Cash equivalents:
Money market funds	$	45	$	—	$	—	$	45	$	30	$	—	$	—	$	30
Investments:
U.S. treasuries		1,144		—		1,144		—		1,138		—		1,138		—
Mortgage backed securities		461		—		461		—		471		—		471		—
Corporate bonds		443		—		443		—		435		—		435		—
U.S. government agency securities		50		—		50		—		49		—		49		—
Asset backed securities		20		—		20		—		10		—		10		—
Restricted cash and investments:
Corporate bonds		177,919		—		177,919		—		181,377		—		181,377		—
Mortgage backed securities		81,816		—		81,816		—		87,400		—		87,400		—
U.S. government agency securities		42,939		—		42,939		—		44,640		—		44,640		—
U.S. treasuries		37,415		—		37,415		—		44,021		—		44,021		—
Money market funds		16,371		—		—		16,371		419		—		—		419
Supranational bonds		4,766		—		4,766		—		4,741		—		4,741		—
Mutual funds		2,264		2,264		—		—		1,093		1,093		—		—
Asset backed securities		130		—		130		—		74		—		74		—
Municipal bonds		50		—		50		—		50		—		50		—
Total investments	$	365,833	$	2,264	$	347,153	$	16,416	$	365,948	$	1,093	$	364,406	$	449

(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 March 31, 2019 and December 31, 2018. Actual maturities may differ from contractual maturities because borrowers may have the right to prepay obligations with or without prepayment penalties.

	March 31, 2019
(In thousands)	Less than 1 Year		Between 1 to 5 Years		Between 5 to 10 Years		Total
Corporate bonds	$	8,986	$	145,521	$	23,855	$	178,362
U.S. government agency securities		6,924		6,762		29,303		42,989
U.S. treasuries		21,351		17,208		—		38,559
Money market funds		16,416		—		—		16,416
Supranational bonds		—		4,766		—		4,766
Asset backed securities		—		150		—		150
Municipal bonds		50		—		—		50
Total	$	53,727	$	174,407	$	53,158	$	281,292

	December 31, 2018
(In thousands)	Less than 1 Year		Between 1 to 5 Years		Between 5 to 10 Years		Total
Corporate bonds	$	14,183	$	144,894	$	22,735	$	181,812
U.S. treasuries		4,919		40,240		—		45,159
U.S. government agency securities		4,788		7,031		32,870		44,689
Supranational bonds		—		4,741		—		4,741
Money market funds		449		—		—		449
Asset backed securities		—		84		—		84
Municipal bonds		50		—		—		50
Total	$	24,389	$	196,990	$	55,605	$	276,984