Investments - (Tables)

3 Months Ended

Mar. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of Investments

At March 31, 2018, investments - debt securities and restricted investments classified as available-for-sale securities were as follows:

	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Investments - debt securities:
U.S. Treasury securities	$	9,926	$	—	$	25	$	9,901
Corporate debt securities	37,515		175		1,245		36,445
	47,441		175		1,270		46,346
Restricted investments:
Short-term bond	3,240		—		13		3,227
Money market funds	165		—		—		165
	3,405		—		13		3,392
	$	50,846	$	175	$	1,283	$	49,738

At December 31, 2017, investments - debt securities, investments - equity securities and restricted investments classified as available-for-sale securities were as follows:

	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Investments - debt securities:
U.S. Treasury securities	$	9,892	$	—	$	22	$	9,870
Corporate debt securities	67,781		411		1,817		66,375
	77,673		411		1,839		76,245
Investments - equity securities:
Preferred stock	35,955		423		1,355		35,023
Restricted investments:
Short-term bond	4,264		—		13		4,251
Money market fund	218		—		—		218
	4,482		—		13		4,469
	$	118,110	$	834	$	3,207	$	115,737

Continuous Unrealized Loss Position

The following table provides the U.S. Treasury securities, corporate debt securities and restricted investments unrealized loss position and related fair values as of March 31, 2018:

	Less Than 12 Months				12 Months or Greater
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investments - debt securities:
U.S. Treasury securities	$	9,901	$	25	$	—	$	—
Corporate debt securities	—		—		21,982		1,245
Restricted investments:
Short-term bond	—		—		3,227		13
	$	9,901	$	25	$	25,209	$	1,258

The following table provides the U.S. Treasury securities, corporate debt securities, preferred stock and restricted investments unrealized loss position and related fair values as of December 31, 2017:

	Less Than 12 Months				12 Months or Greater
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investments - debt securities:
U.S. Treasury securities	$	9,870	$	22	$	—	$	—
Corporate debt securities	15,515		691		29,595		1,126
Investments - equity securities:
Preferred stock	11,263		1,337		1,986		18
Restricted investments:
Short-term bond	—		—		4,251		13
	$	36,648	$	2,050	$	35,832	$	1,157

Contractual Maturities of Investments

The net carrying value and estimated fair value of investments - debt securities and restricted investments classified as available-for-sale at March 31, 2018, 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	$	12,601	$	12,431
Due after one year through five years	34,771		33,866
Due after five years through ten years	69		49
	47,441		46,346
Restricted investments	3,405		3,392
	$	50,846	$	49,738