Investments (Summary of Gross Unrealized Losses for Investments that have been Continiously in Unrealized Loss Position) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Schedule of Investments [Line Items]
Fair Value 12 months or less	$ 100,603	$ 81,876
Unrealized Losses 12 months or less	(2,824)	(1,047)
Fair Value Longer than 12 months	52,052	50,039
Unrealized Losses Longer than 12 months	(2,475)	(3,782)
Total Fair Value	152,655	131,915
Total Unrealized Losses	(5,299)	(4,829)
Equity Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	2,157	3,363
Unrealized Losses 12 months or less	(1,137)	(515)
Total Fair Value	2,157	3,363
Total Unrealized Losses	(1,137)	(515)
Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	98,446	78,513
Unrealized Losses 12 months or less	(1,687)	(532)
Fair Value Longer than 12 months	52,052	50,039
Unrealized Losses Longer than 12 months	(2,475)	(3,782)
Total Fair Value	150,498	128,552
Total Unrealized Losses	(4,162)	(4,314)
Us Treasury Securities and Obligations of U.S. Government [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	3,992	23,998
Unrealized Losses 12 months or less	(4)	(3)
Total Fair Value	3,992	23,998
Total Unrealized Losses	(4)	(3)
Corporate Bonds [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	4,684	10,802
Unrealized Losses 12 months or less	(95)	(38)
Fair Value Longer than 12 months	6,515	6,910
Unrealized Losses Longer than 12 months	(608)	(725)
Total Fair Value	11,199	17,712
Total Unrealized Losses	(703)	(763)
Collateralized Corporate Bank Loans [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	41,465	6,273
Unrealized Losses 12 months or less	(239)	(97)
Fair Value Longer than 12 months	7,337	14,236
Unrealized Losses Longer than 12 months	(218)	(646)
Total Fair Value	48,802	20,509
Total Unrealized Losses	(457)	(743)
Municipal Bonds [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	32,585	30,073
Unrealized Losses 12 months or less	(600)	(362)
Fair Value Longer than 12 months	38,042	28,809
Unrealized Losses Longer than 12 months	(1,645)	(2,408)
Total Fair Value	70,627	58,882
Total Unrealized Losses	(2,245)	(2,770)
Mortgage Backed [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	15,720	7,367
Unrealized Losses 12 months or less	(749)	(32)
Fair Value Longer than 12 months	158	84
Unrealized Losses Longer than 12 months	(4)	(3)
Total Fair Value	15,878	7,451
Total Unrealized Losses	(753)	(35)
Financial Services [Member] | Equity Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less		92
Unrealized Losses 12 months or less		(1)
Total Fair Value		92
Total Unrealized Losses		(1)
All Other [Member] | Equity Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	2,157	3,271
Unrealized Losses 12 months or less	(1,137)	(514)
Total Fair Value	2,157	3,271
Total Unrealized Losses	$ (1,137)	$ (514)