Investments (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Partnership Loan Investment Agreement Security	Dec. 31, 2012 Security	Dec. 31, 2011
Major Categories of Investment Income [Line Items]
Investment Income	$ 11,238	$ 12,216	$ 12,814
Investment expenses	(2,468)	(2,286)	(2,085)
Net investment income	8,770	9,930	10,729
Schedule of Available-For-Sale Securities [Line Items]
Applicable federal income taxes	(26,432)	(19,098)
Net unrealized gains - net of tax	49,089	35,467
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Number of Securities, Total	516	259
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair value, total	145,056	123,485
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross unrealized loss, total	(4,584)	(2,937)
Gain and Loss on Investment [Abstract]
Limited partnerships - net gain (loss)	7,995	7,052	(21,890)
Total net gains (losses)	23,515	9,011	(17,803)
Shareholders' equity, net of deferred federal income taxes and undistributed earnings from limited partnership	24,461
Adjustments for other-than-temporary impairment [Roll Forward]
Cumulative charges to income at beginning of year	7,773	8,178	7,604
Writedowns based on objective and subjective criteria	742	888	1,906
Recovery of prior write-downs upon sale or disposal	(1,745)	(1,293)	(1,332)
Net pre-tax realized gain (loss)	1,003	405	(574)
Cumulative charges to income at end of year	6,770	7,773	8,178
Addition (reduction) to earnings per share from net after tax realized gain (loss) (in dollars per share)	$ 0.04	$ 0.02	$ (0.03)
Unrealized gain on investments previously written down at end of the year - see note below	13,129	8,158	6,782
Committed funds for bridge loans	12,000
Number of bridge loan agreements	2
Limited Partners' Capital Account [Line Items]
Number of partnerships investment	3
Market value of equity and fixed maturity securities portfolio managed by broker dealers	2,760	19,427
Total commissions and net fees earned by broker dealers and affiliates	239	186	174
Summarized financial information of significant limited partnership investments [Abstract]
Total assets	1,072,270	983,024
Regulatory deposits with various insurance departments in United States and Canada, fair value	63,447	47,791
Time certificate of deposit included in short-term investments	4,891
Percentage of fixed maturities invested in investment grade fixed maturity (in hundredths)	89.00%
Total fixed maturity investments	20,324
Number of different investments in fixed maturity	11
Number of different third party insurance companies issuing fixed maturity investments with guarantees	3
Amount of largest exposure to a single investment	4,035
Fixed maturity investment below investment grade	44,800
Percentage of fixed maturity investment to total invested assets (in hundredths)	6.40%
Number of investments in diversified portfolio including catastrophe bonds	40
Net unrealized loss position of diversified portfolio	662
Committed funds	12,000
Number of bridge loan	2
Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Commitment to make additional contributions to various limited partnerships	6,315
Total investment in three limited partnerships	23,000
Number of partnerships investment	3
Aggregate estimated value of limited partnership	39,899
Number of directors that are executive officers, directors, and owners of the organization managing the limited partnership	3
Ownership interest in limited partnership, minimum (in hundredths)	4.00%
Ownership interest in limited partnership, maximum (in hundredths)	14.00%
Investment gains (losses), net of fees	1,154	2,485	(18,673)
Management fees	640	650	793
Performance-based fees	18	0	0
Summarized financial information of significant limited partnership investments [Abstract]
Total partners' capital	39,899
Significant Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
Aggregate estimated value of limited partnership	444,337	559,745	579,568
Number of significant investments in public and private equity market in India	1
Significant investment in public and private equity markets in India, value	22,692	25,868
Estimated ownership interest in significant limited partnership investment (in hundredths)	4.00%
Earnings from significant limited partnership investment	(3,176)	2,404	(9,732)
Summarized financial information of significant limited partnership investments [Abstract]
Total assets	493,028	641,071	633,165
Total partners' capital	444,337	559,745	579,568
Net increase in partners' capital resulting from operations	(64,550)	60,734	(266,314)
U.S. Government Obligations [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	113,389	70,742
Cost or Amortized Cost	113,348	70,720
Gross Unrealized Gains	81	43
Gross Unrealized Losses	(40)	(21)
Net Unrealized Gains (losses)	41	22
Residential mortgage-backed securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	13,252	25,040
Cost or Amortized Cost	12,058	23,954
Gross Unrealized Gains	1,334	1,218
Gross Unrealized Losses	(140)	(132)
Net Unrealized Gains (losses)	1,194	1,086
Commercial Mortgage-backed Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	28,565	11,828
Cost or Amortized Cost	28,406	11,006
Gross Unrealized Gains	308	849
Gross Unrealized Losses	(149)	(27)
Net Unrealized Gains (losses)	159	822
State and Municipal Obligations [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	115,250	194,865
Cost or Amortized Cost	115,278	194,258
Gross Unrealized Gains	407	757
Gross Unrealized Losses	(435)	(150)
Net Unrealized Gains (losses)	(28)	607
Corporate Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	137,215	120,596
Cost or Amortized Cost	136,991	118,574
Gross Unrealized Gains	3,207	2,923
Gross Unrealized Losses	(2,983)	(901)
Net Unrealized Gains (losses)	224	2,022
Foreign Government Obligations [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	23,879	22,598
Cost or Amortized Cost	23,689	22,047
Gross Unrealized Gains	588	602
Gross Unrealized Losses	(398)	(51)
Net Unrealized Gains (losses)	190	551
Fixed Maturities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	431,550	445,669
Cost or Amortized Cost	429,770	440,559
Gross Unrealized Gains	5,925	6,392
Gross Unrealized Losses	(4,145)	(1,282)
Net Unrealized Gains (losses)	1,780	5,110
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Number of Securities 12 months or less	451	170
Number of Securities Greater than 12 months	53	58
Number of Securities, Total	504	228
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair value, 12 months or less	123,145	90,607
Fair value, Greater than 12 months	18,249	19,283
Fair value, total	141,394	109,890
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross unrealized loss, less than 12 months	(3,105)	(483)
Gross unrealized loss, 12 months or longer	(1,040)	(799)
Gross unrealized loss, total	(4,145)	(1,282)
Average unrealized loss for securities in loss position (in hundredths)	3.00%
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
One year or less	99,367
Excess of one year to five years	197,404
Excess of five years to ten years	54,287
Excess of ten years	6,258
Total maturities	357,316
Asset-backed securities	74,234
Available-for-sale Securities, Debt Securities, Total	431,550
Percentage of Available for sale Securities, Debt Maturities, Fair Value [Abstract]
One year or less (in hundredths)	23.00%
Excess of one year to five years (in hundredths)	45.70%
Excess of five years to ten years (in hundredths)	12.60%
Excess of ten years (in hundredths)	1.50%
Total maturities (in hundredths)	82.80%
Asset-backed securities (in hundredths)	17.20%
Available-for-sale Securities, Debt Securities, Total (in hundredths)	100.00%
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
One year or less	98,926
Excess of one year to five years	198,046
Excess of five years to ten years	53,719
Excess of ten years	5,838
Total maturities	356,529
Asset-backed securities	73,241
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	429,770
Percentage of Available for sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
One year or less (in hundredths)	23.00%
Excess of one year to five years (in hundredths)	46.10%
Excess of five years to ten years (in hundredths)	12.50%
Excess of ten years (in hundredths)	1.40%
Total maturities (in hundredths)	83.00%
Asset-backed securities (in hundredths)	17.00%
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total (in hundredths)	100.00%
Gain and Loss on Investment [Abstract]
Gross gains	7,235	3,860	6,443
Gross losses	(4,371)	(3,961)	(6,805)
Net gains (losses)	2,864	(101)	(362)
Financial Institutions [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	18,850	12,394
Cost or Amortized Cost	7,780	5,925
Gross Unrealized Gains	11,171	6,542
Gross Unrealized Losses	(101)	(73)
Net Unrealized Gains (losses)	11,070	6,469
Industrial & Miscellaneous [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	126,978	95,188
Cost or Amortized Cost	64,307	52,202
Gross Unrealized Gains	63,009	44,568
Gross Unrealized Losses	(338)	(1,582)
Net Unrealized Gains (losses)	62,671	42,986
Equity Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	145,828	107,582
Cost or Amortized Cost	72,087	58,127
Gross Unrealized Gains	74,180	51,110
Gross Unrealized Losses	(439)	(1,655)
Net Unrealized Gains (losses)	73,741	49,455
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Number of Securities 12 months or less	10	20
Number of Securities Greater than 12 months	2	11
Number of Securities, Total	12	31
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair value, 12 months or less	1,682	6,955
Fair value, Greater than 12 months	1,980	6,640
Fair value, total	3,662	13,595
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross unrealized loss, less than 12 months	(204)	(842)
Gross unrealized loss, 12 months or longer	(235)	(813)
Gross unrealized loss, total	(439)	(1,655)
Gain and Loss on Investment [Abstract]
Gross gains	15,374	3,191	7,409
Gross losses	(2,718)	(1,131)	(2,960)
Net gains (losses)	12,656	2,060	4,449
Total Available-for-Sale Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	577,378	553,251
Cost or Amortized Cost	501,857	498,686
Gross Unrealized Gains	80,105	57,502
Gross Unrealized Losses	(4,584)	(2,937)
Net Unrealized Gains (losses)	75,521	54,565
Fixed Maturities [Member]
Major Categories of Investment Income [Line Items]
Investment Income	9,023	10,052	11,016
Equity Securities [Member]
Major Categories of Investment Income [Line Items]
Investment Income	2,166	2,121	1,738
Money Market Funds, Short term and Other [Member]
Major Categories of Investment Income [Line Items]
Investment Income	$ 49	$ 43	$ 60