Investments (Tables)

12 Months Ended

Dec. 31, 2018

Investments [Abstract]

Amortized Cost and Estimated Fair Value of Investments in Debt and Equity Securities

The amortized cost and estimated fair value of investments in debt and equity securities by category is as follows (in thousands):

			Gross		Gross
			Unrealized		Unrealized
	Amortized Cost		Gains		Losses		Fair Value
As of December 31, 2018
U.S. Treasury securities and obligations of U.S. Government	$	48,609	$	5	$	(508)	$	48,106
Corporate bonds		243,314		440		(1,602)		242,152
Collateralized corporate bank loans		131,779		19		(5,270)		126,528
Municipal bonds		112,574		3,791		(838)		115,527
Mortgage-backed		13,992		11		(446)		13,557
Total debt securities		550,268		4,266		(8,664)		545,870
Total equity securities		68,709		20,693		(8,506)		80,896
Total other investments		3,763		—		(2,615)		1,148
Total investments	$	622,740	$	24,959	$	(19,785)	$	627,914
As of December 31, 2017
U.S. Treasury securities and obligations of U.S. Government	$	50,088	$	7	$	(148)	$	49,947
Corporate bonds		278,611		1,204		(742)		279,073
Collateralized corporate bank loans		125,536		702		(301)		125,937
Municipal bonds		134,052		709		(505)		134,256
Mortgage-backed		16,712		37		(216)		16,533
Total debt securities		604,999		2,659		(1,912)		605,746
Total equity securities		30,253		23,014		(1,504)		51,763
Total other investments		3,763		61		—		3,824
Total investments	$	639,015	$	25,734	$	(3,416)	$	661,333

Major Categories of Investment Income

Major categories of net investment income are summarized as follows (in thousands):

	Twelve Months Ended December 31,
	2018		2017
U.S. Treasury securities and obligations of U.S. Government	$	902	$	566
Corporate bonds		6,696		7,839
Collateralized corporate bank loans		5,658		4,302
Municipal bonds		3,757		4,633
Mortgage-backed		521		1,049
Equity securities		1,151		871
Other investments		—		—
Cash and cash equivalents		518		706
		19,203		19,966
Investment expenses		(971)		(1,092)
Investment income, net of expenses	$	18,232	$	18,874

Major Categories of Net Realized Gains on Investments

Major categories of net investment gains (losses) on investments are summarized as follows (in thousands):

	Twelve Months Ended December 31,
	2018		2017
U.S. Treasury securities and obligations of U.S. Government	$	—	$	—
Corporate bonds		(83)		(468)
Collateralized corporate bank loans		90		79
Municipal bonds		1,435		195
Mortgage-backed		2		(9)
Equity securities		359		7,002
Gain on investments		1,803		6,799
Unrealized loss on other investments		(2,676)		(1,127)
Other-than-temporary impairments		—		(5,877)
Unrealized losses on equity investments		(9,322)		—
Investment losses, net	$	(10,195)	$	(205)

Summary of Gross Unrealized Loss Position

The following schedules summarize the gross unrealized losses showing the length of time that investments have been continuously in an unrealized loss position as of December 31, 2018 and December 31, 2017 (in thousands):

	As of December 31, 2018
	12 months or less				Longer than 12 months				Total
			Unrealized				Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
U.S. Treasury securities and obligations of U.S. Government	$	18,902	$	(181)	$	28,201	$	(327)	$	47,103	$	(508)
Corporate bonds		117,450		(907)		100,060		(695)		217,510		(1,602)
Collateralized corporate bank loans		120,410		(4,938)		4,931		(332)		125,341		(5,270)
Municipal bonds		14,281		(96)		25,891		(742)		40,172		(838)
Mortgage-backed		6,592		(60)		5,986		(386)		12,578		(446)
Total debt securities		277,635		(6,182)		165,069		(2,482)		442,704		(8,664)
Total equity securities		30,981		(3,699)		4,475		(4,807)		35,456		(8,506)
Total other investments		1,148		(2,615)		—		—		1,148		(2,615)
Total investments	$	309,764	$	(12,496)	$	169,544	$	(7,289)	$	479,308	$	(19,785)

	As of December 31, 2017
	12 months or less				Longer than 12 months				Total
			Unrealized				Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
U.S. Treasury securities and obligations of U.S. Government	$	28,825	$	(145)	$	1,997	$	(3)	$	30,822	$	(148)
Corporate bonds		176,061		(736)		2,378		(6)		178,439		(742)
Collateralized corporate bank loans		30,008		(280)		2,517		(21)		32,525		(301)
Municipal bonds		35,200		(370)		8,917		(135)		44,117		(505)
Mortgage-backed		6,419		(127)		1,415		(89)		7,834		(216)
Total debt securities		276,513		(1,658)		17,224		(254)		293,737		(1,912)
Total equity securities		8,375		(1,504)		—		—		8,375		(1,504)
Total other investments		—		—		—		—		—		—
Total investments	$	284,888	$	(3,162)	$	17,224	$	(254)	$	302,112	$	(3,416)

Carrying Value of Other Invested Assets Portfolio

Details regarding the carrying value of the other invested assets portfolio as of December 31, 2018 and 2017 were as follows:

	2018		2017
Investment Type
Equity warrant	$	1,148	$	3,824
Total other investments	$	1,148	$	3,824

Schedule of Amortized Cost and Estimated Fair Value of Debt Securities

The amortized cost and estimated fair value of debt securities at December 31, 2018 by contractual maturity are as follows. Expected maturities may differ from contractual maturities because certain borrowers may have the right to call or prepay obligations with or without penalties.

	Amortized Cost		Fair Value
	(in thousands)
Due in one year or less	$	119,771	$	120,127
Due after one year through five years		284,992		284,947
Due after five years through ten years		105,656		102,047
Due after ten years		25,857		25,192
Mortgage-backed		13,992		13,557
	$	550,268	$	545,870