SCHEDULE II CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments other than subsidiaries:
Fixed maturities	$ 451,809				$ 431,550				$ 451,809	$ 431,550
Limited partnerships	81,230				68,988				81,230	68,988
Total Investments	698,112				651,257				698,112	651,257
Cash and cash equivalents	64,632				59,297				64,632	59,297	71,549
Accounts receivable	98,144				100,830				98,144	100,830
Other assets	9,413				19,051				9,413	19,051
Total Assets	1,144,247				1,072,270				1,144,247	1,072,270
Liabilities:
Total Liabilities	744,751				690,546				744,751	690,546
Shareholders' equity:
Additional paid-in capital	51,854				50,594				51,854	50,594
Unrealized net gains on investments	51,840				49,089				51,840	49,089
Foreign exchange adjustment	390				1,401				390	1,401
Retained earnings	294,773				280,003				294,773	280,003	258,358	241,325
Shareholders' equity	399,496				381,724				399,496	381,724	346,712	319,061
Total liabilities and shareholders' equity	1,144,247				1,072,270				1,144,247	1,072,270
Revenue:
Commissions and service fees									6,430	5,944	5,722
Net investment income	2,599	2,073	2,090	2,294	2,183	2,192	1,985	2,410	9,055	8,770	9,930
Net realized losses on investments									14,930	23,515	9,011
Total revenue									292,042	290,972	262,124
Expenses:
Other									88,048	85,361	77,430
Total expenses									247,644	236,062	215,518
Income before federal income taxes and equity in undistributed income of subsidiaries									44,398	54,910	46,606
Federal income tax benefit									14,681	18,322	14,687
Equity in undistributed income (loss) of subsidiaries									7,108	7,995	7,052
Net income	8,246	5,770	9,340	6,361	8,967	7,771	4,907	14,943	29,717	36,588	31,919
Condensed Statements of Cash Flows
Net cash provided by operating activities									30,160	35,907	55,794
Investing activities:
Distributions from limited partnerships									1,752	2,528	3,957
Net cash used in investing activities									(18,867)	(32,641)	(59,302)
Financing activities:
Dividends paid to shareholders									(14,947)	(14,943)	(14,886)
Net cash used in financing activities									(4,947)	(14,943)	(14,886)
Increase (decrease) in cash and cash equivalents									5,335	(12,252)	(18,177)
Cash and cash equivalents at beginning of year				59,297				71,549	59,297	71,549	89,726
Cash and cash equivalents at end of year	64,632				59,297				64,632	59,297	71,549
Class A [Member]
Shareholders' equity:
Common stock	112				112				112	112
Class B [Member]
Shareholders' equity:
Common stock	527				525				527	525
Parent Company [Member]
Assets
Investment in subsidiaries	415,304				398,008				415,304	398,008
Due from affiliates	2,762				2,465				2,762	2,465
Investments other than subsidiaries:
Fixed maturities	11,924				11,093				11,924	11,093
Limited partnerships	233				248				233	248
Total Investments	12,157				11,341				12,157	11,341
Cash and cash equivalents	16,615				9,848				16,615	9,848	12,143
Accounts receivable	5,157				7,075				5,157	7,075
Other assets	17,905				13,453				17,905	13,453
Total Assets	469,900				442,190				469,900	442,190
Liabilities:
Premiums payable	27,850				30,004				27,850	30,004
Deposits from insureds	18,303				16,307				18,303	16,307
Notes payable to bank	20,000				10,000				20,000	10,000
Other liabilities	4,251				4,155				4,251	4,155
Total Liabilities	70,404				60,466				70,404	60,466
Shareholders' equity:
Additional paid-in capital	51,854				50,594				51,854	50,594
Unrealized net gains on investments	51,840				49,089				51,840	49,089
Foreign exchange adjustment	390				1,401				390	1,401
Retained earnings	294,773				280,003				294,773	280,003
Shareholders' equity	399,496				381,724				399,496	381,724
Total liabilities and shareholders' equity	469,900				442,190				469,900	442,190
Revenue:
Commissions and service fees									22,153	21,597	20,753
Dividends from subsidiaries									15,000	15,000	14,000
Net investment income									102	54	48
Net realized losses on investments									(27)	(11)	(49)
Other									126	41	24
Total revenue									37,354	36,681	34,776
Expenses:
Salary and related items									15,543	15,965	15,410
Other									7,978	6,633	7,098
Total expenses									23,521	22,598	22,508
Income before federal income taxes and equity in undistributed income of subsidiaries									13,833	14,083	12,268
Federal income tax benefit									(294)	(348)	(629)
Income (loss)									14,127	14,431	12,897
Equity in undistributed income (loss) of subsidiaries									15,590	22,157	19,022
Net income									29,717	36,588	31,919
Condensed Statements of Cash Flows
Net cash provided by operating activities									19,719	15,125	20,735
Investing activities:
Purchases of long-term investments									(6,398)	(10,322)	(8,944)
Sales or maturities of long-term investments									5,253	9,982	8,902
Decrease in notes receivable from employees									0	0	1,252
Distributions from limited partnerships									13	0	0
Net purchases of property and equipment									(6,873)	(1,775)	(834)
Other									0	(362)	228
Net cash used in investing activities									(8,005)	(2,477)	604
Financing activities:
Dividends paid to shareholders									(14,947)	(14,943)	(14,886)
Drawings on line of credit									10,000	0	0
Net cash used in financing activities									(4,947)	(14,943)	(14,886)
Increase (decrease) in cash and cash equivalents									6,767	(2,295)	6,453
Cash and cash equivalents at beginning of year				9,848				12,143	9,848	12,143	5,690
Cash and cash equivalents at end of year	16,615				9,848				16,615	9,848	12,143
Parent Company [Member] | Class A [Member]
Shareholders' equity:
Common stock	112				112				112	112
Parent Company [Member] | Class B [Member]
Shareholders' equity:
Common stock	$ 527				$ 525				$ 527	$ 525