Investment Securities (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost	$ 641,994,000	$ 736,861,000
Unrealized Gains	28,342,000	17,092,000
Unrealized Losses	(1,797,000)	(9,073,000)
Fair Value	668,539,000	744,880,000
Interest in a limited partnership	600,000	1,400,000
Bonds:
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost	639,616,000	725,462,000
Unrealized Gains	28,312,000	16,925,000
Unrealized Losses	(1,744,000)	(7,249,000)
Fair Value	666,184,000	735,138,000
U.S. government and government sponsored entities
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost	33,955,000	52,912,000
Unrealized Gains	2,487,000	2,005,000
Fair Value	36,442,000	54,917,000
Obligations of states, municipalities, and political subdivisions
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost	135,476,000	192,287,000
Unrealized Gains	4,997,000	4,584,000
Unrealized Losses	(249,000)	(484,000)
Fair Value	140,224,000	196,387,000
Corporate debt
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost	278,555,000	325,116,000
Unrealized Gains	10,514,000	3,803,000
Unrealized Losses	(1,380,000)	(5,609,000)
Fair Value	287,689,000	323,310,000
RMBS
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost	164,308,000	120,605,000
Unrealized Gains	7,948,000	4,632,000
Unrealized Losses	(47,000)	(23,000)
Fair Value	172,209,000	125,214,000
CMBS
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost	11,964,000	16,239,000
Unrealized Gains	1,152,000	1,634,000
Unrealized Losses	(64,000)	(597,000)
Fair Value	13,052,000	17,276,000
CDO/ABS
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost	15,358,000	18,303,000
Unrealized Gains	1,214,000	267,000
Unrealized Losses	(4,000)	(536,000)
Fair Value	16,568,000	18,034,000
Preferred stocks
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost		4,959,000
Unrealized Losses		(163,000)
Fair Value		4,796,000
Other long-term investments
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost	1,404,000	5,599,000
Unrealized Gains		167,000
Unrealized Losses	(24,000)	(1,639,000)
Fair Value	1,380,000	4,127,000
Common stocks
Cost/amortized cost, unrealized gains and losses, and fair value of investment securities by type, which are classified as available-for-sale
Cost/Amortized Cost	974,000	841,000
Unrealized Gains	30,000
Unrealized Losses	(29,000)	(22,000)
Fair Value	$ 975,000	$ 819,000