Fair Value (Details) (USD $) In Thousands, unless otherwise specified					9 Months Ended
	Sep. 30, 2012 Carrying Value [Member]	Dec. 31, 2011 Carrying Value [Member]	Sep. 30, 2012 Fair Value [Member]	Dec. 31, 2011 Fair Value [Member]	Sep. 30, 2012 Insurance Linked Securities [Member]	Sep. 30, 2011 Insurance Linked Securities [Member]	Sep. 30, 2012 Insurance Linked Securities [Member] Maximum [Member]	Sep. 30, 2012 Insurance Linked Securities [Member] Minimum [Member]	Sep. 30, 2012 Level 1 [Member] Fair Value [Member]	Dec. 31, 2011 Level 1 [Member] Fair Value [Member]	Sep. 30, 2012 Level 2 [Member] Fair Value [Member]	Dec. 31, 2011 Level 2 [Member] Fair Value [Member]	Sep. 30, 2012 Level 3 [Member] Fair Value [Member]	Dec. 31, 2011 Level 3 [Member] Fair Value [Member]	Sep. 30, 2012 Recurring [Member]	Dec. 31, 2011 Recurring [Member]	Sep. 30, 2012 Recurring [Member] Level 1 [Member]	Dec. 31, 2011 Recurring [Member] Level 1 [Member]	Sep. 30, 2012 Recurring [Member] Level 2 [Member]	Dec. 31, 2011 Recurring [Member] Level 2 [Member]	Sep. 30, 2012 Recurring [Member] Level 3 [Member]	Dec. 31, 2011 Recurring [Member] Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
US government obligations															$ 70,686	$ 73,137	$ 70,686	$ 73,137	$ 0	$ 0	$ 0	$ 0
Government sponsored entities																349		0		349		0
Residential mortgage-backed securities															16,808	21,872	0	0	16,808	21,872	0	0
Commercial mortgage-backed securities															14,717	11,300	0	0	14,717	11,300	0	0
State and municipal obligations															195,300	190,035	0	0	195,300	190,035	0	0
Corporate securities															122,628	90,141	0	0	108,682	73,091	13,946	17,050
Options embedded in convertible securities															1,612	1,505	0	0	1,612	1,505	0	0
Foreign government obligations															21,833	21,121	0	0	21,833	21,121	0	0
Total fixed maturities															443,584	409,460	70,686	73,137	358,952	319,273	13,946	17,050
Equity securities															103,882	88,085	103,882	88,085	0	0	0	0
Short term															3,580	3,675	3,580	2,982	0	693	0	0
Cash equivalents															62,903	81,756	0	0	62,903	81,756	0	0
Total fair value															613,949	582,976	178,148	164,204	421,855	401,722	13,946	17,050
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Sales					0	0
Transfers into Level 3					0	0
Transfers out of Level 3					0	0
Percentage of variance in values of securities (in hundredths)							3.00%	0.00%
Fair value assets measured on recurring basis unobservable input reconciliation calculation [Roll Forward]
Beginning of period balance					17,050	17,242
Total gain or losses (realized or unrealized) included in earnings (or changes in net assets)					140	387
Purchases					400	6,522
Settlements					(3,644)	(7,101)
End of period balance					13,946	17,050
Assets [Abstract]
Limited partnerships	59,237	54,705	59,237	54,705					0	0	0	0	59,237	54,705
Liabilities [Abstract]
Short-term borrowings	$ 10,000	$ 10,000	$ 10,000	$ 10,000					$ 0	$ 0	$ 10,000	$ 10,000	$ 0	$ 0