Investments (Tables)

9 Months Ended

Sep. 30, 2016

Investments, Debt and Equity Securities [Abstract]

Schedule of Investments

At September 30, 2016, investments and restricted investments classified as available-for-sale securities were as follows:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Debt securities:
U.S. Treasury securities	$	99,659	$	75	$	—	$	99,734
Corporate debt securities	111,963		2,349		622		113,690
Preferred stock	22,930		397		95		23,232
	234,552		2,821		717		236,656
Restricted investments:
Money market fund	5,640		—		—		5,640
	$	240,192	$	2,821	$	717	$	242,296

At December 31, 2015, investments and restricted investments classified as available-for-sale securities were as follows:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Debt securities:
U.S. Treasury securities	$	184,819	$	—	$	79	$	184,740
Corporate debt securities	7,273		—		981		6,292
Preferred stock	265		—		57		208
	192,357		—		1,117		191,240
Restricted investments:
Guaranteed income fund	7,072		—		—		7,072
	$	199,429	$	—	$	1,117	$	198,312

Continuous Unrealized Loss Position

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

	As of September 30, 2016								As of December 31, 2015
	Less Than 12 Months				12 Months or Greater				Less Than 12 Months				12 Months or Greater
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Debt securities:
U.S. Treasury securities	$	—	$	—	$	—	$	—	$	184,740	$	79	$	—	$	—
Corporate debt securities	14,367		232		4,912		390		6,292		981		—		—
Preferred stock	169		95		—		—		208		57		—		—
	$	14,536	$	327	$	4,912	$	390	$	191,240	$	1,117	$	—	$	—

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, 2016, by contractual maturity are shown in the following table. Actual maturities may differ from contractual maturities because certain borrowers have the right to call or prepay obligations.

	Amortized Cost		Fair Value
Due in one year or less	$	113,393	$	113,944
Due after one year through five years	98,130		99,398
Due after ten years through fifteen years	99		82
	211,622		213,424
Preferred stock	22,930		23,232
Restricted investments	5,640		5,640
	$	240,192	$	242,296