Investments (Tables)

12 Months Ended

Dec. 31, 2017

Gross Unrealized Gains and Losses and Amortized Cost and Fair Value of Investments Classified as Held-to-maturity

The gross unrealized gains and losses on, and the amortized cost and fair value of, those investments classified as held-to-maturity at December 31, 2017 are summarized as follows:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
States and political subdivisions	$	460,428	$	9,628	$	(955	)	$	469,101
Corporate bonds		100,024		190		(167	)		100,047
Commercial mortgage-backed securities		—		—		—			—
U.S. agency-based mortgage-backed securities		10,260		625		(40	)		10,845
U.S. Treasury securities and obligations      of U.S. government agencies		57,657		548		(198	)		58,007
Asset-backed securities		1,299		25		(15	)		1,309
Totals	$	629,668	$	11,016	$	(1,375	)	$	639,309

The gross unrealized gains and losses on, and the amortized cost and fair value of, those investments classified as held-to-maturity at December 31, 2016 are summarized as follows:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
States and political subdivisions	$	394,875	$	7,622	$	(3,014	)	$	399,483
Corporate bonds		143,858		423		(265	)		144,016
Commercial mortgage-backed securities		70		—		—			70
U.S. agency-based mortgage-backed securities		9,967		948		—			10,915
U.S. Treasury securities and obligations      of U.S. government agencies		11,737		746		(67	)		12,416
Asset-backed securities		1,927		163		(59	)		2,031
Totals	$	562,434	$	9,902	$	(3,405	)	$	568,931

Gross Unrealized Gains and Losses and Cost or Amortized Cost and Fair Value of Investments Classified as Available-for-sale

The gross unrealized gains and losses on, and the cost or amortized cost and fair value of, those investments classified as available-for-sale at December 31, 2017 are summarized as follows:

	Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
Fixed maturity:
States and political subdivisions	$	244,898	$	6,819	$	(577	)	$	251,140
Corporate bonds		130,210		224		(212	)		130,222
U.S. agency-based mortgage-backed securities		18,813		—		(799	)		18,014
U.S. Treasury securities and obligations      of U.S. government agencies		67,315		29		(1,126	)		66,218
Total fixed maturity		461,236		7,072		(2,714	)		465,594
Equity securities		8,503		779		—			9,282
Other investments		—		—		—			—
Totals	$	469,739	$	7,851	$	(2,714	)	$	474,876

The gross unrealized gains and losses on, and the cost or amortized cost and fair value of, those investments classified as available-for-sale at December 31, 2016 are summarized as follows:

	Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
Fixed maturity:
States and political subdivisions	$	231,168	$	4,340	$	(3,215	)	$	232,293
Corporate bonds		182,350		436		(271	)		182,515
U.S. agency-based mortgage-backed securities		10,428		17		(1,103	)		9,342
U.S. Treasury securities and obligations      of U.S. government agencies		55,925		—		(978	)		54,947
Total fixed maturity		479,871		4,793		(5,567	)		479,097
Equity securities		—		33		—			33
Other investments		10,000		3,330		—			13,330
Totals	$	489,871	$	8,156	$	(5,567	)	$	492,460

A Summary of the Company's Realized Gains and Losses on Sales, Calls or Redemptions of Investments

A summary of the Company’s realized gains and losses on sales, calls or redemptions of investments for 2017, 2016 and 2015 is as follows:

	Fixed Maturity Securities Available for Sale			Equity Securities		Other			Total
	(in thousands)
Year ended December 31, 2017
Proceeds from sales	$	14,591		$	1	$	13,172		$	27,764
Gross realized investment gains	$	485		$	1	$	—		$	486
Gross realized investment (losses)		(5	)		—		—			(5	)
Net realized investment gains		480			1		—			481
Other, including losses on calls and redemptions		(520	)		—		(608	)		(1,128	)
Net realized gains (losses) on investments	$	(40	)	$	1	$	(608	)	$	(647	)
Year ended December 31, 2016
Proceeds from sales	$	54,730		$	—	$	4,609		$	59,339
Gross realized investment gains	$	823		$	—	$	68		$	891
Gross realized investment (losses)		(1,728	)		—		—			(1,728	)
Net realized investment gains (losses)		(905	)		—		68			(837	)
Other, including gains on calls and redemptions		274			—		69			343
Net realized gains (losses) on investments	$	(631	)	$	—	$	137		$	(494	)
Year ended December 31, 2015
Proceeds from sales	$	4,432		$	—	$	—		$	4,432
Gross realized investment gains	$	177		$	—	$	—		$	177
Gross realized investment (losses)		(162	)		—		—			(162	)
Net realized investment gains		15			—		—			15
Impairments		(2,653	)		—		—			(2,653	)
Other, including gains on calls and redemptions		102			—		42			144
Net realized gains (losses) on investments	$	(2,536	)	$	—	$	42		$	(2,494	)

Major Categories of the Company's Net Investment Income

Major categories of the Company’s net investment income are summarized as follows:

	Year Ended December 31,
	2017			2016			2015
	(in thousands)
Gross investment income:
Fixed maturity securities	$	28,961		$	27,837		$	28,498
Equity securities		201			—			—
Short-term investments and cash and cash equivalents		1,117			348			149
Other investments		104			1,568			763
Total gross investment income		30,383			29,753			29,410
Investment expenses		(1,102	)		(1,647	)		(1,508	)
Net investment income	$	29,281		$	28,106		$	27,902

Investment Securities Continuous Unrealized Loss Position

The following table summarizes the fair value and gross unrealized losses on securities, aggregated by major investment category and length of time that the individual securities have been in a continuous unrealized loss position:

	Less Than 12 Months				12 Months or Greater				Total
	Fair Value of Investments with Unrealized Losses		Gross Unrealized Losses		Fair Value of Investments with Unrealized Losses		Gross Unrealized Losses		Fair Value of Investments with Unrealized Losses		Gross Unrealized Losses
	(in thousands)
December 31, 2017
Held-to-Maturity
Fixed maturity securities:
States and political subdivisions	$	110,698	$	654	$	19,895	$	301	$	130,593	$	955
Corporate bonds		56,425		156		4,121		11		60,546		167
U.S. agency-based mortgage-backed securities		2,798		40		—		—		2,798		40
U.S. Treasury securities and obligations      of U.S. government agencies		48,153		122		3,948		76		52,101		198
Asset-backed securities		—		—		967		15		967		15
Total held-to-maturity securities		218,074		972		28,931		403		247,005		1,375
Available-for Sale
Fixed maturity securities:
States and political subdivisions	$	23,365	$	86	$	19,153	$	491	$	42,518	$	577
Corporate bonds		82,795		171		5,888		41		88,683		212
U.S. agency-based mortgage-backed securities		14,686		59		3,328		740		18,014		799
U.S. Treasury securities and obligations      of U.S. government agencies		14,730		204		47,716		922		62,446		1,126
Total available-for-sale securities		135,576		520		76,085		2,194		211,661		2,714
Total	$	353,650	$	1,492	$	105,016	$	2,597	$	458,666	$	4,089
December 31, 2016
Held-to-Maturity
Fixed maturity securities:
States and political subdivisions	$	157,507	$	3,014	$	—	$	—	$	157,507	$	3,014
Corporate bonds		44,654		202		6,292		63		50,946		265
U.S. Treasury securities and obligations      of U.S. government agencies		3,968		67		—		—		3,968		67
Asset-backed securities		—		—		1,173		59		1,173		59
Total held-to-maturity securities		206,129		3,283		7,465		122		213,594		3,405
Available-for Sale
Fixed maturity securities:
States and political subdivisions	$	73,505	$	2,976	$	4,523	$	239	$	78,028	$	3,215
Corporate bonds		41,419		111		7,922		160		49,341		271
U.S. agency-based mortgage-backed securities		3,702		48		3,607		1,055		7,309		1,103
U.S. Treasury securities and obligations      of U.S. government agencies		54,947		978		—		—		54,947		978
Total available-for-sale securities		173,573		4,113		16,052		1,454		189,625		5,567
Total	$	379,702	$	7,396	$	23,517	$	1,576	$	403,219	$	8,972

Held-to-Maturity Securities [Member]

Summary of Amortized Cost and Fair Value of Investments in Fixed Maturity Securities, by Contractual Maturity

A summary of the amortized cost and fair value of investments in fixed maturity securities, classified as held-to-maturity at December 31, 2017, by contractual maturity, is as follows:

	Amortized Cost		Fair Value
	(in thousands)
Maturity:
Within one year	$	88,215	$	88,556
After one year through five years		271,580		273,810
After five years through ten years		98,748		100,745
After ten years		159,566		164,044
U.S. agency-based mortgage-backed securities		10,260		10,845
Asset-backed securities		1,299		1,309
Totals	$	629,668	$	639,309

Available-for-Sale Securities [Member]

Summary of Amortized Cost and Fair Value of Investments in Fixed Maturity Securities, by Contractual Maturity

A summary of the amortized cost and fair value of investments in fixed maturity securities, classified as available-for-sale at December 31, 2017, by contractual maturity, is as follows:

	Amortized Cost		Fair Value
	(in thousands)
Maturity:
Within one year	$	76,194	$	76,211
After one year through five years		153,483		153,092
After five years through ten years		43,442		43,606
After ten years		169,304		174,671
U.S. agency-based mortgage-backed securities		18,813		18,014
Totals	$	461,236	$	465,594