Investments - (Tables)

9 Months Ended

Sep. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Schedule of Investments

At September 30, 2017, investments and restricted investments classified as available-for-sale securities were as follows:

	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Investments:
U.S. Treasury securities	$	9,995	$	1	$	—	$	9,996
Corporate debt securities	103,251		778		2,522		101,507
Preferred stock	33,923		708		898		33,733
	147,169		1,487		3,420		145,236
Restricted investments:
Short-term bond	4,239		6		—		4,245
Money market funds	217		—		—		217
	4,456		6		—		4,462
	$	151,625	$	1,493	$	3,420	$	149,698

At December 31, 2016, investments and restricted investments classified as available-for-sale securities were as follows:

	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Investments:
Corporate debt securities	$	135,590	$	5,311	$	1,769	$	139,132
Preferred stock	36,048		656		111		36,593
	171,638		5,967		1,880		175,725
Restricted investments:
Short-term bond	4,232		—		6		4,226
Money market fund	1,410		—		—		1,410
	5,642		—		6		5,636
	$	177,280	$	5,967	$	1,886	$	181,361

Continuous Unrealized Loss Position

The following table provides the corporate debt securities, preferred stock and restricted investments unrealized loss position and related fair values:

	As of September 30, 2017								As of December 31, 2016
	Less Than 12 Months				12 Months or Greater				Less Than 12 Months				12 Months or Greater
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investments:
Corporate debt securities	42,178		2,034		28,142		488		64,516		1,410		6,971		359
Preferred stock	11,729		871		169		27		—		—		153		111
Restricted investments:
Short-term bond	—		—		—		—		4,226		6		—		—
	$	53,907	$	2,905	$	28,311	$	515	$	68,742	$	1,416	$	7,124	$	470

Contractual Maturities of Investments

The net carrying value and estimated fair value of investments and restricted investments classified as available-for-sale at September 30, 2017, by contractual maturity are shown in the following table. Actual maturities may differ from contractual maturities since certain borrowers have the right to call or prepay obligations.

	Amortized Cost		Fair Value
Due in one year or less	$	13,974	$	13,944
Due after one year through five years	95,423		93,476
Due after five year through ten years	3,757		4,025
Due after ten years through fifteen years	92		58
	113,246		111,503
Preferred stock	33,923		33,733
Restricted investments	4,456		4,462
	$	151,625	$	149,698