Investments (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2016 USD ($) Director Security Partnership Investment	Dec. 31, 2015 USD ($) Security	Dec. 31, 2014 USD ($)
Net Investment Income [Line Items]
Investment Income		$ 16,980	$ 15,140	$ 11,536
Investment expenses		(2,497)	(2,642)	(2,481)
Net investment income		14,483	12,498	9,055
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Fair value		611,849	582,682
Cost or amortized cost		559,463	522,799
Gross unrealized gains		60,621	74,527
Gross unrealized losses		(8,235)	(14,644)
Net unrealized gains (losses)		52,386	59,883
Applicable federal income taxes		(18,335)	(20,959)
Net unrealized gains - net of tax		$ 34,051	$ 38,924
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Number of Securities, total | Security		486	569
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair value, total		$ 343,800	$ 340,035
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross unrealized loss, total		(8,235)	(14,644)
Gain and Loss on Investment [Abstract]
Limited partnerships - net gain (loss)		2,473	(1,687)	7,108
Total net gains (losses)		23,228	(1,261)	14,930
Shareholders' equity, net of deferred federal income taxes and undistributed earnings from limited partnership		28,110
Adjustments for other-than-temporary impairment [Roll Forward]
Cumulative charges to income at beginning of year		10,513	7,168	6,770
Writedowns based on objective and subjective criteria		5,743	7,700	689
Recovery of prior writedowns upon sale or disposal		(12,260)	(4,355)	(291)
Net pre-tax realized gain (loss)		6,517	(3,345)	(398)
Cumulative charges to income at end of year		3,996	10,513	7,168
Unrealized gain on investments previously written down at end of the year	[1]	$ 2,108	14,710	17,127
Limited Partners' Capital Account [Line Items]
Number of partnerships investment | Partnership		3
Aggregate estimated value in limited partnership		$ 44,038	45,009
Market value of equity and fixed maturity securities portfolio managed by broker dealers		41,706
Total commissions and net fees earned by broker dealers and affiliates		207	235	212
Summarized financial information of significant limited partnership investments [Abstract]
Total assets		1,154,137	1,085,771
Total partners' capital		44,038	45,009
Regulatory deposits with various insurance departments in United States and Canada, fair value		86,169	84,198
Time certificate of deposit included in short-term investments		$ 1,500
Percentage of fixed maturities invested in investment grade fixed maturity		85.00%
Total fixed maturity investments		$ 719
Number of different investments in fixed maturity | Investment		1
Fixed maturity investment below investment grade		$ 69,112
Percentage of fixed maturity investment to total invested assets		9.20%
Number of investments in diversified portfolio including catastrophe bonds | Investment		40
Net unrealized loss position of diversified portfolio		$ 951
Directors [Member]
Limited Partners' Capital Account [Line Items]
Number of company employees employed by investment firm | Director		2
Agency Collateralized Mortgage Obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		$ 6,171	0
Cost or amortized cost		6,000	0
Gross unrealized gains		171	0
Gross unrealized losses		0	0
Net unrealized gains (losses)		171	0
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		6,171	0
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		6,000	0
Agency Mortgage Backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		4,770	3,157
Cost or amortized cost		4,751	3,159
Gross unrealized gains		57	38
Gross unrealized losses		(38)	(40)
Net unrealized gains (losses)		19	(2)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		4,770	3,157
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		4,751	3,159
Asset-backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		45,183	44,309
Cost or amortized cost		45,207	45,941
Gross unrealized gains		458	393
Gross unrealized losses		(482)	(2,025)
Net unrealized gains (losses)		(24)	(1,632)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		45,183	44,309
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		45,207	45,941
Bank Loans [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		10,349	5,060
Cost or amortized cost		10,222	5,333
Gross unrealized gains		149	4
Gross unrealized losses		(22)	(277)
Net unrealized gains (losses)		127	(273)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		10,349	5,060
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		10,222	5,333
Certificates of Deposit [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		3,117	3,230
Cost or amortized cost		3,126	3,247
Gross unrealized gains		0	0
Gross unrealized losses		(9)	(17)
Net unrealized gains (losses)		(9)	(17)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		3,117	3,230
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		3,126	3,247
Collateralized Mortgage Obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		9,104	9,257
Cost or amortized cost		9,096	9,282
Gross unrealized gains		290	116
Gross unrealized losses		(282)	(141)
Net unrealized gains (losses)		8	(25)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		9,104	9,257
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		9,096	9,282
Corporate Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		142,683	110,511
Cost or amortized cost		143,356	112,615
Gross unrealized gains		1,643	2,123
Gross unrealized losses		(2,316)	(4,227)
Net unrealized gains (losses)		(673)	(2,104)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		142,683	110,511
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		143,356	112,615
Mortgage-backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		24,571	23,892
Cost or amortized cost		23,904	24,138
Gross unrealized gains		1,132	243
Gross unrealized losses		(465)	(489)
Net unrealized gains (losses)		667	(246)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		24,571	23,892
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		23,904	24,138
Municipal Obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		129,335	110,578
Cost or amortized cost		130,204	109,932
Gross unrealized gains		391	805
Gross unrealized losses		(1,260)	(159)
Net unrealized gains (losses)		(869)	646
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		129,335	110,578
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		130,204	109,932
Non-U.S. Government Obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		24,681	23,945
Cost or amortized cost		26,461	25,483
Gross unrealized gains		230	342
Gross unrealized losses		(2,010)	(1,880)
Net unrealized gains (losses)		(1,780)	(1,538)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		24,681	23,945
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		26,461	25,483
U.S. Government Obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		91,940	103,245
Cost or amortized cost		92,234	103,448
Gross unrealized gains		74	56
Gross unrealized losses		(368)	(259)
Net unrealized gains (losses)		(294)	(203)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value		91,940	103,245
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost		92,234	103,448
Total Fixed Maturities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value		491,904	437,184
Cost or amortized cost		494,561	442,578
Gross unrealized gains		4,595	4,120
Gross unrealized losses		(7,252)	(9,514)
Net unrealized gains (losses)		$ (2,657)	$ (5,394)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Number of Securities 12 months or less | Security		397	328
Number of Securities Greater than 12 months | Security		54	168
Number of Securities, total | Security		451	496
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair value, 12 months or less		$ 291,048	$ 205,475
Fair value, Greater than 12 months		32,054	108,043
Fair value, total		323,102	313,518
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross unrealized loss, less than 12 months		(4,380)	(5,070)
Gross unrealized loss, 12 months or longer		(2,872)	(4,444)
Gross unrealized loss, total		(7,252)	(9,514)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
One year or less, Fair Value		87,661
Excess of one year to five years, Fair Value		273,874
Excess of five years to ten years, Fair Value		35,553
Excess of ten years, Fair Value		5,017
Total maturities, Fair Value		402,105
Asset-backed securities, Fair Value		89,799
Total, Fair Value		$ 491,904	437,184
Percentage of Available for sale Securities, Debt Maturities, Fair Value [Abstract]
One year or less, Fair Value		17.80%
Excess of one year to five years, Fair Value		55.70%
Excess of five years to ten years, Fair Value		7.20%
Excess of ten years, Fair Value		1.00%
Total maturities, Fair Value		81.70%
Asset-backed securities, Fair Value		18.30%
Total, Fair Value		100.00%
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
One year or less, Cost or Amortized Cost		$ 88,139
Excess of one year to five years, Cost or Amortized Cost		276,995
Excess of five years to ten years, Cost or Amortized Cost		35,409
Excess of ten years, Cost or Amortized Cost		5,060
Total maturities, Cost or Amortized Cost		405,603
Asset-backed securities, Cost or Amortized Cost		88,958
Cost or amortized cost		$ 494,561	442,578
Percentage of Available for sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
One year or less, Cost or Amortized Cost		17.80%
Excess of one year to five years, Cost or Amortized Cost		56.00%
Excess of five years to ten years, Cost or Amortized Cost		7.20%
Excess of ten years, Cost or Amortized Cost		1.00%
Total maturities, Cost or Amortized Cost		82.00%
Asset-backed securities, Cost or Amortized Cost		18.00%
Cost or amortized cost		100.00%
Gain and Loss on Investment [Abstract]
Gross gains		$ 11,628	6,633	6,480
Gross losses		(14,020)	(13,634)	(4,596)
Net gains (losses)		(2,392)	(7,001)	1,884
Consumer [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value		32,576	46,541
Cost or amortized cost		15,231	16,849
Gross unrealized gains		17,656	30,535
Gross unrealized losses		(311)	(843)
Net unrealized gains (losses)		17,345	29,692
Energy [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value		12,842	8,635
Cost or amortized cost		5,641	6,152
Gross unrealized gains		7,203	3,323
Gross unrealized losses		(2)	(840)
Net unrealized gains (losses)		7,201	2,483
Financial [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value		31,186	35,686
Cost or amortized cost		22,417	24,173
Gross unrealized gains		8,998	12,265
Gross unrealized losses		(229)	(752)
Net unrealized gains (losses)		8,769	11,513
Industrial [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value		21,145	24,841
Cost or amortized cost		6,239	9,325
Gross unrealized gains		15,098	15,840
Gross unrealized losses		(192)	(324)
Net unrealized gains (losses)		14,906	15,516
Technology [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value		8,858	11,596
Cost or amortized cost		4,117	6,153
Gross unrealized gains		4,769	5,546
Gross unrealized losses		(28)	(103)
Net unrealized gains (losses)		4,741	5,443
Mutual Fund [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value		6,995	9,983
Cost or amortized cost		6,930	11,022
Gross unrealized gains		121	69
Gross unrealized losses		(56)	(1,108)
Net unrealized gains (losses)		65	(1,039)
Other [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value		6,343	8,216
Cost or amortized cost		4,327	6,547
Gross unrealized gains		2,181	2,829
Gross unrealized losses		(165)	(1,160)
Net unrealized gains (losses)		2,016	1,669
Total Equity Securities [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value		119,945	145,498
Cost or amortized cost		64,902	80,221
Gross unrealized gains		56,026	70,407
Gross unrealized losses		(983)	(5,130)
Net unrealized gains (losses)		$ 55,043	$ 65,277
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Number of Securities 12 months or less | Security		35	73
Number of Securities Greater than 12 months | Security		0	0
Number of Securities, total | Security		35	73
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair value, 12 months or less		$ 20,698	$ 26,517
Fair value, Greater than 12 months		0	0
Fair value, total		20,698	26,517
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross unrealized loss, less than 12 months		(983)	(5,130)
Gross unrealized loss, 12 months or longer		0	0
Gross unrealized loss, total		(983)	(5,130)
Gain and Loss on Investment [Abstract]
Gross gains		28,742	21,070	7,467
Gross losses		(5,595)	(13,643)	(1,529)
Net gains (losses)		23,147	7,427	5,938
Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Commitment to make additional contributions to various limited partnerships		1,627
Total investment in three limited partnerships		$ 23,000
Number of partnerships investment | Partnership		3
Aggregate estimated value in limited partnership		$ 44,038
Number of directors that are executive officers, directors, and owners of the organization managing the limited partnership | Director		4
Investment gains (losses), net of fees		$ (971)	(1,978)	7,088
Management fees		796	749	697
Summarized financial information of significant limited partnership investments [Abstract]
Total partners' capital		$ 44,038
Limited Partnership [Member] | Minimum [Member]
Limited Partners' Capital Account [Line Items]
Ownership interest in limited partnership		6.00%
Limited Partnership [Member] | Maximum [Member]
Limited Partners' Capital Account [Line Items]
Ownership interest in limited partnership		37.00%
Significant Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Aggregate estimated value in limited partnership		$ 408,275	470,783	542,700
Number of significant investments in public and private equity market in India | Investment		1
Significant investment in public and private equity markets in India, value		$ 27,153	28,270
Estimated ownership interest in significant limited partnership investment		6.00%
Earnings (losses) from limited partnership investment		$ (1,117)	(1,599)	7,176
Summarized financial information of significant limited partnership investments [Abstract]
Total assets		448,263	511,118	565,500
Total partners' capital		408,275	470,783	542,700
Net increase (decrease) in partners' capital resulting from operations		(15,679)	(19,603)	125,700
Total Fixed Maturities [Member]
Net Investment Income [Line Items]
Investment Income		13,254	11,663	8,806
Total Equity Securities [Member]
Net Investment Income [Line Items]
Investment Income		3,598	3,445	2,693
Money Market Funds, Short term and Other [Member]
Net Investment Income [Line Items]
Investment Income		$ 128	$ 32	$ 37

[1] Recovery in market value of an investment which has previously been adjusted for other-than-temporary impairment is treated as an unrealized gain until the investment matures or is sold.