Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 segment	Sep. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Number of business segments			2
Net premiums earned	$ 212,021	$ 194,219	$ 607,189	$ 557,403
Investment income, net of investment expenses	22,837	27,278	77,202	82,761
Net realized investment gains (losses)	894	1,190	5,796	7,250
Other income (loss)	113	337	1,255	634
Total revenues	235,865	223,024	691,442	648,048
Net income (loss)	325	11,725	24,341	49,614
Assets	3,825,328	3,723,697	3,825,328	3,723,697	3,720,672
Invested assets	3,138,948	3,037,677	3,138,948	3,037,677	3,050,137
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Number of business locations	7		7
Total revenues	203,261	191,205	598,087	551,879
Net income (loss)	(1,880)	10,282	19,471	44,207
Assets	2,094,173	1,977,120	2,094,173	1,977,120
Invested assets	1,515,753	1,401,982	1,515,753	1,401,982
Life Insurance [Member]
Segment Reporting Information [Line Items]
Total revenues	32,604	31,819	93,355	96,169
Net income (loss)	2,205	1,443	4,870	5,407
Assets	1,731,155	1,746,577	1,731,155	1,746,577
Invested assets	1,623,195	1,635,695	1,623,195	1,635,695
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net premiums earned	212,153	194,342	607,586	557,772
Investment income, net of investment expenses	22,838	27,266	77,146	82,676
Net realized investment gains (losses)	894	1,190	5,796	7,250
Other income (loss)	113	337	1,255	634
Total revenues	235,998	223,135	691,783	648,332
Operating Segments [Member] | Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Net premiums earned	195,195	178,553	562,521	511,781
Investment income, net of investment expenses	8,191	11,679	31,135	34,379
Net realized investment gains (losses)	(22)	816	3,682	5,405
Other income (loss)	(102)	145	693	229
Total revenues	203,262	191,193	598,031	551,794
Operating Segments [Member] | Life Insurance [Member]
Segment Reporting Information [Line Items]
Net premiums earned	16,958	15,789	45,065	45,991
Investment income, net of investment expenses	14,647	15,587	46,011	48,297
Net realized investment gains (losses)	916	374	2,114	1,845
Other income (loss)	215	192	562	405
Total revenues	32,736	31,942	93,752	96,538
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Total revenues	(133)	(111)	(341)	(284)
Intersegment Elimination [Member] | Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Total revenues	(1)	12	56	85
Intersegment Elimination [Member] | Life Insurance [Member]
Segment Reporting Information [Line Items]
Total revenues	$ (132)	$ (123)	$ (397)	$ (369)