Investments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Investments, Amortized Cost	$ 427,171	$ 411,043
Investments, Gross Unrealized Gains	18,108	20,059
Investments, Gross Unrealized Losses	(5,495)	(6,474)
Investments, Fair Value	439,784	424,628
Equity Securities [Member]
Investments, Amortized Cost	30,119	30,465
Investments, Gross Unrealized Gains	10,807	14,017
Investments, Gross Unrealized Losses	(211)	(323)
Investments, Fair Value	40,715	44,159
Debt Securities [Member]
Investments, Amortized Cost	397,052	380,578
Investments, Gross Unrealized Gains	7,301	6,042
Investments, Gross Unrealized Losses	(5,284)	(6,151)
Investments, Fair Value	399,069	380,469
US Treasury Securities and Obligation [Member] | Debt Securities [Member]
Investments, Amortized Cost	15,119	11,152
Investments, Gross Unrealized Gains	13	24
Investments, Gross Unrealized Losses	(5)	0
Investments, Fair Value	15,127	11,176
Corporate Bond Securities [Member] | Debt Securities [Member]
Investments, Amortized Cost	100,613	93,272
Investments, Gross Unrealized Gains	2,602	2,305
Investments, Gross Unrealized Losses	(1,193)	(1,655)
Investments, Fair Value	102,022	93,922
Collateralized Corporate Bank Loans [Member] | Debt Securities [Member]
Investments, Amortized Cost	109,853	94,638
Investments, Gross Unrealized Gains	320	175
Investments, Gross Unrealized Losses	(1,310)	(1,920)
Investments, Fair Value	108,863	92,893
Municipal Bonds [Member] | Debt Securities [Member]
Investments, Amortized Cost	167,940	177,432
Investments, Gross Unrealized Gains	4,280	3,458
Investments, Gross Unrealized Losses	(2,765)	(2,549)
Investments, Fair Value	169,455	178,341
Collateralized Mortgage Backed Securities [Member] | Debt Securities [Member]
Investments, Amortized Cost	3,527	4,084
Investments, Gross Unrealized Gains	86	80
Investments, Gross Unrealized Losses	(11)	(27)
Investments, Fair Value	3,602	4,137
Equity Securities Financial Services [Member] | Equity Securities [Member]
Investments, Amortized Cost	10,999	11,618
Investments, Gross Unrealized Gains	3,298	4,463
Investments, Gross Unrealized Losses	(3)	(260)
Investments, Fair Value	14,294	15,821
Equity Securities, Other [Member] | Equity Securities [Member]
Investments, Amortized Cost	19,120	18,847
Investments, Gross Unrealized Gains	7,509	9,554
Investments, Gross Unrealized Losses	(208)	(63)
Investments, Fair Value	$ 26,421	$ 28,338