Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 segments	Mar. 31, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Number of business segments	2
Net premiums earned	$ 193,341	$ 176,817
Investment income, net of investment expenses	26,762	26,464
Net realized investment gains (losses)	2,194	1,909
Other income	607	115
Total revenues	222,904	205,305
Net income	13,331	22,393
Assets	3,769,249	3,724,690	3,720,672
Invested assets	3,115,734	3,063,359	3,050,137
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Number of business locations	7
Total revenues	192,504	174,227
Net income	11,811	20,730
Assets	2,032,501	1,941,227
Invested assets	1,486,783	1,378,188
Life Insurance [Member]
Segment Reporting Information [Line Items]
Total revenues	30,400	31,078
Net income	1,520	1,663
Assets	1,736,748	1,783,463
Invested assets	1,628,951	1,685,171
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net premiums earned	193,474	176,940
Investment income, net of investment expenses	26,712	26,400
Net realized investment gains (losses)	2,194	1,909
Other income	607	115
Total revenues	222,987	205,364
Operating Segments [Member] | Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Net premiums earned	179,494	162,701
Investment income, net of investment expenses	11,113	10,421
Net realized investment gains (losses)	1,367	1,029
Other income	480	12
Total revenues	192,454	174,163
Operating Segments [Member] | Life Insurance [Member]
Segment Reporting Information [Line Items]
Net premiums earned	13,980	14,239
Investment income, net of investment expenses	15,599	15,979
Net realized investment gains (losses)	827	880
Other income	127	103
Total revenues	30,533	31,201
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Total revenues	(83)	(59)
Intersegment Elimination [Member] | Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Total revenues	50	64
Intersegment Elimination [Member] | Life Insurance [Member]
Segment Reporting Information [Line Items]
Total revenues	$ (133)	$ (123)