Investments (Tables)

3 Months Ended

Mar. 31, 2020

Investments

Schedule of Investments

	March 31, 2020
			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		(Losses)		Fair Value
Investments - debt securities:
U.S. Treasury Bills	$	49,944	$	18	$	(14)	$	49,948
Corporate debt securities		178		—		(129)		49
		50,122		18		(143)		49,997
Restricted investments:
Short-term bond		1,165		—		(7)		1,158
		1,165		—		(7)		1,158
	$	51,287	$	18	$	(150)	$	51,155

	December 31, 2019
			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		(Losses)		Fair Value
Investments - debt securities:
Corporate debt securities	$	178	$	—	$	(125)	$	53
		178		—		(125)		53
Restricted investments:
Short-term bond		2,239		11		—		2,250
Money market fund		114		—		—		114
		2,353		11		—		2,364
	$	2,531	$	11	$	(125)	$	2,417

Schedule of Unrealized Loss Position and Related Fair Value of Investments

	March 31, 2020
	Less Than 12 Months				12 Months or Greater
			Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses
Investments - debt securities:
U.S. Treasury Bills	$	42,949	$	14	$	—	$	—
Corporate debt securities		—		—		49		129
Restricted investments:
Short-term bond		—		—		1,158		7
	$	42,949	$	14	$	1,207	$	136

	December 31, 2019
	Less Than 12 Months				12 Months or Greater
			Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses
Investments - debt securities:
Corporate debt securities	$	—	$	—	$	53	$	125

Schedule of Contractual Maturities of Investments

	March 31, 2020
	Amortized Cost		Fair Value
Due in one year or less	$	50,122	$	49,997
Restricted investments		1,165		1,158
	$	51,287	$	51,155