Investments (Tables)

3 Months Ended

Mar. 31, 2019

Investments

Schedule of Investments

	March 31, 2019
			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		(Losses)		Fair Value
Investments - debt securities:
U.S. Treasury securities	$	6,978	$	1	$	—	$	6,979
Corporate debt securities		2,927		—		(89)		2,838
		9,905		1		(89)		9,817
Restricted investments:
Short-term bond		2,210		5		—		2,215
Money market fund		113		—		—		113
		2,323		5		—		2,328
	$	12,228	$	6	$	(89)	$	12,145

	December 31, 2018
			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		(Losses)		Fair Value
Investments - debt securities:
U.S. Treasury securities	$	6,936	$	1	$	—	$	6,937
Corporate debt securities		2,908		—		(887)		2,021
		9,844		1		(887)		8,958
Restricted investments:
Short-term bond		3,274		—		(9)		3,265
Money market fund		167		—		—		167
		3,441		—		(9)		3,432
	$	13,285	$	1	$	(896)	$	12,390

Schedule of Unrealized Loss Position and Related Fair Value of Investments

	March 31, 2019
	Less Than 12 Months				12 Months or Greater
			Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses
Investments - debt securities:
Corporate debt securities	$	—	$	—	$	2,838	$	89

	December 31, 2018
	Less Than 12 Months				12 Months or Greater
			Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses
Investments - debt securities:
Corporate debt securities	$	—	$	—	$	1,843	$	887
Restricted investments:
Short-term bond		—		—		3,265		9
	$	—	$	—	$	5,108	$	896

Schedule of Contractual Maturities of Investments

	March 31, 2019
	Amortized Cost		Fair Value
Due in one year or less	$	9,905	$	9,817
Restricted investments		2,323		2,328
	$	12,228	$	12,145