Investments (Tables)

6 Months Ended

Jun. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Schedule of Investments

At June 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	$	24,930	$	—	$	7	$	24,923
Corporate debt securities	97,563		713		2,257		96,019
Preferred stock	40,525		855		1,103		40,277
Common stock	6,481		165		123		6,523
	169,499		1,733		3,490		167,742
Restricted investments:
Short-term bond	4,254		—		4		4,250
Money market funds	219		—		—		219
	4,473		—		4		4,469
	$	173,972	$	1,733	$	3,494	$	172,211

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 U.S. Treasury securities, corporate debt securities, preferred stock, common stock and restricted investments unrealized loss position and related fair values:

	As of June 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:
U.S. Treasury securities	$	24,923	$	7	$	—	$	—	$	—	$	—	$	—	$	—
Corporate debt securities	49,758		1,394		9,542		863		64,516		1,410		6,971		359
Preferred stock	11,544		1,055		147		48		—		—		153		111
Common stock	3,054		123		—		—		—		—		—		—
Restricted investments:
Short-term bond	4,250		4		—		—		4,226		6		—		—
	$	93,529	$	2,583	$	9,689	$	911	$	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 June 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	$	28,886	$	28,584
Due after one year through five years	92,165		90,963
Due after five year through ten years	1,351		1,339
Due after ten years through fifteen years	91		56
	122,493		120,942
Preferred stock	40,525		40,277
Common stock	6,481		6,523
Restricted investments	4,473		4,469
	$	173,972	$	172,211