Investments (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) Director Security Agreement Partnership Investment $ / shares	Dec. 31, 2014 USD ($) Security $ / shares	Dec. 31, 2013 USD ($) $ / shares
Major Categories of Investment Income [Line Items]
Investment Income	$ 15,140	$ 11,536	$ 11,238
Investment expenses	(2,642)	(2,481)	(2,468)
Net investment income	12,498	9,055	8,770
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Applicable federal income taxes	(20,959)	(27,913)
Net unrealized gains - net of tax	$ 38,924	$ 51,840
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Number of Securities, Total | Security	569	767
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair value, total	$ 340,035	$ 218,647
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross unrealized loss, total	(14,644)	(9,724)
Gain and Loss on Investment [Abstract]
Limited partnerships - net gain (loss)	(1,687)	7,108	7,995
Total net gains (losses)	(1,261)	14,930	23,515
Shareholders' equity, net of deferred federal income taxes and undistributed earnings from limited partnership	26,512
Adjustments for other-than-temporary impairment [Roll Forward]
Cumulative charges to income at beginning of year	7,168	6,770	7,773
Writedowns based on objective and subjective criteria	7,700	689	742
Recovery of prior writedowns upon sale or disposal	(4,355)	(291)	(1,745)
Net pre-tax realized gain (loss)	(3,345)	(398)	1,003
Cumulative charges to income at end of year	$ 10,513	$ 7,168	$ 6,770
Addition (reduction) to earnings per share from net after-tax OTI gain (loss) (in dollars per share) | $ / shares	$ (0.14)	$ (0.02)	$ 0.04
Unrealized gain on investments previously written down at end of the year - see note below	$ 14,710	$ 17,127	$ 13,129
Committed funds for bridge loans	$ 5,000
Number of bridge loan agreements | Agreement	1
Limited Partners' Capital Account [Line Items]
Number of partnerships investment | Partnership	2
Aggregate estimated value of limited partnership	$ 45,009	46,987
Market value of equity and fixed maturity securities portfolio managed by broker dealers	62,156
Total commissions and net fees earned by broker dealers and affiliates	235	212	239
Summarized financial information of significant limited partnership investments [Abstract]
Total assets	1,085,771	1,144,247
Total partners' capital	45,009	46,987
Regulatory deposits with various insurance departments in United States and Canada, fair value	84,198	76,406
Time certificate of deposit included in short-term investments	$ 2,220
Percentage of fixed maturities invested in investment grade fixed maturity	85.00%
Total fixed maturity investments	$ 2,969
Number of different investments in fixed maturity | Investment	3
Number of different third party insurance companies issuing fixed maturity investments with guarantees | Investment	3
Amount of largest exposure to a single investment	$ 1,997
Fixed maturity investment below investment grade	$ 61,271
Percentage of fixed maturity investment to total invested assets	8.40%
Number of investments in diversified portfolio including catastrophe bonds | Investment	40
Net unrealized loss position of diversified portfolio	$ 3,185
Directors [Member]
Limited Partners' Capital Account [Line Items]
Number of company employees employed by investment firm | Director	2
U.S. Government Obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	$ 103,245	101,094
Cost or amortized cost	103,448	101,058
Gross unrealized gains	56	108
Gross unrealized losses	(259)	(72)
Net unrealized gains (losses)	(203)	36
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Securities, Total	103,245	101,094
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost	103,448	101,058
Residential Mortgage-Backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	4,776	6,066
Cost or amortized cost	4,668	5,830
Gross unrealized gains	162	273
Gross unrealized losses	(54)	(37)
Net unrealized gains (losses)	108	236
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Securities, Total	4,776	6,066
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost	4,668	5,830
Commercial Mortgage-backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	30,595	36,440
Cost or amortized cost	30,977	36,210
Gross unrealized gains	247	630
Gross unrealized losses	(629)	(400)
Net unrealized gains (losses)	(382)	230
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Securities, Total	30,595	36,440
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost	30,977	36,210
State and Municipal Obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	110,578	113,777
Cost or amortized cost	109,932	113,133
Gross unrealized gains	806	784
Gross unrealized losses	(160)	(140)
Net unrealized gains (losses)	646	644
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Securities, Total	110,578	113,777
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost	109,932	113,133
Corporate Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	164,025	166,966
Cost or amortized cost	168,137	170,822
Gross unrealized gains	2,445	2,005
Gross unrealized losses	(6,557)	(5,861)
Net unrealized gains (losses)	(4,112)	(3,856)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Securities, Total	164,025	166,966
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost	168,137	170,822
Foreign Government Obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	23,965	27,466
Cost or amortized cost	25,416	28,332
Gross unrealized gains	404	114
Gross unrealized losses	(1,855)	(980)
Net unrealized gains (losses)	(1,451)	(866)
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Securities, Total	23,965	27,466
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Cost or amortized cost	25,416	28,332
Total Fixed Maturities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	437,184	451,809
Cost or amortized cost	442,578	455,385
Gross unrealized gains	4,120	3,914
Gross unrealized losses	(9,514)	(7,490)
Net unrealized gains (losses)	$ (5,394)	$ (3,576)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Number of Securities 12 months or less | Security	328	591
Number of Securities Greater than 12 months | Security	168	140
Number of Securities, Total | Security	496	731
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair value, 12 months or less	$ 205,475	$ 176,756
Fair value, Greater than 12 months	108,043	27,667
Fair value, total	313,518	204,423
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross unrealized loss, less than 12 months	(5,070)	(6,083)
Gross unrealized loss, 12 months or longer	(4,444)	(1,407)
Gross unrealized loss, total	$ (9,514)	(7,490)
Average unrealized loss for securities in loss position	3.00%
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
One year or less	$ 74,187
Excess of one year to five years	242,713
Excess of five years to ten years	36,452
Excess of ten years	3,218
Total maturities	356,570
Asset-backed securities	80,614
Available-for-sale Securities, Debt Securities, Total	$ 437,184	451,809
Percentage of Available for sale Securities, Debt Maturities, Fair Value [Abstract]
One year or less	17.00%
Excess of one year to five years	55.50%
Excess of five years to ten years	8.30%
Excess of ten years	0.80%
Total maturities	81.60%
Asset-backed securities	18.40%
Available-for-sale Securities, Debt Securities, Total	100.00%
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
One year or less	$ 75,854
Excess of one year to five years	244,033
Excess of five years to ten years	37,269
Excess of ten years	2,901
Total maturities	360,057
Asset-backed securities	82,521
Cost or amortized cost	$ 442,578	455,385
Percentage of Available for sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
One year or less	17.10%
Excess of one year to five years	55.10%
Excess of five years to ten years	8.40%
Excess of ten years	0.70%
Total maturities	81.30%
Asset-backed securities	18.70%
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	100.00%
Gain and Loss on Investment [Abstract]
Gross gains	$ 6,633	6,480	7,235
Gross losses	(13,634)	(4,596)	(4,371)
Net gains (losses)	(7,001)	1,884	2,864
Financial Institutions [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value	21,694	25,343
Cost or amortized cost	10,836	10,100
Gross unrealized gains	11,069	15,303
Gross unrealized losses	(211)	(60)
Net unrealized gains (losses)	10,858	15,243
Industrial & Miscellaneous [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value	123,804	136,764
Cost or amortized cost	69,385	68,678
Gross unrealized gains	59,338	70,260
Gross unrealized losses	(4,919)	(2,174)
Net unrealized gains (losses)	54,419	68,086
Total Equity Securities [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value	145,498	162,107
Cost or amortized cost	80,221	78,778
Gross unrealized gains	70,407	85,563
Gross unrealized losses	(5,130)	(2,234)
Net unrealized gains (losses)	$ 65,277	$ 83,329
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Number of Securities 12 months or less | Security	73	33
Number of Securities Greater than 12 months | Security	0	3
Number of Securities, Total | Security	73	36
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair value, 12 months or less	$ 26,517	$ 13,538
Fair value, Greater than 12 months	0	686
Fair value, total	26,517	14,224
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross unrealized loss, less than 12 months	(5,130)	(2,170)
Gross unrealized loss, 12 months or longer	0	(64)
Gross unrealized loss, total	(5,130)	(2,234)
Gain and Loss on Investment [Abstract]
Gross gains	21,070	7,467	15,374
Gross losses	(13,643)	(1,529)	(2,718)
Net gains (losses)	7,427	5,938	12,656
Total Available-for-Sale Securities [Member]
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Fair value	582,682	613,916
Cost or amortized cost	522,799	534,163
Gross unrealized gains	74,527	89,477
Gross unrealized losses	(14,644)	(9,724)
Net unrealized gains (losses)	59,883	79,753
Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Commitment to make additional contributions to various limited partnerships	2,459
Total investment in three limited partnerships	$ 23,000
Number of partnerships investment | Partnership	2
Aggregate estimated value of limited partnership	$ 45,009
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	$ (1,978)	7,088	1,154
Management fees	749	697	640
Performance-based fees	0	0	18
Summarized financial information of significant limited partnership investments [Abstract]
Total partners' capital	$ 45,009
Limited Partnership [Member] | Minimum [Member]
Limited Partners' Capital Account [Line Items]
Ownership interest in limited partnership	5.00%
Limited Partnership [Member] | Maximum [Member]
Limited Partners' Capital Account [Line Items]
Ownership interest in limited partnership	17.00%
Significant Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Aggregate estimated value of limited partnership	$ 470,783	542,700	444,337
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	$ 28,270	29,868
Estimated ownership interest in significant limited partnership investment	5.00%
Earnings from significant limited partnership investment	$ (1,599)	7,176	(3,176)
Summarized financial information of significant limited partnership investments [Abstract]
Total assets	511,118	565,500	493,028
Total partners' capital	470,783	542,700	444,337
Net increase (decrease) in partners' capital resulting from operations	(19,603)	125,700	(64,550)
Total Fixed Maturities [Member]
Major Categories of Investment Income [Line Items]
Investment Income	11,663	8,806	9,023
Total Equity Securities [Member]
Major Categories of Investment Income [Line Items]
Investment Income	3,445	2,693	2,166
Money Market Funds, Short term and Other [Member]
Major Categories of Investment Income [Line Items]
Investment Income	$ 32	$ 37	$ 49