Investments (Summary of Gross Unrealized Losses for Investments that have been Continuously in Unrealized Loss Position) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Fair Value 12 months or less	$ 149,686	$ 158,413
Unrealized Losses 12 months or less	(2,438)	(2,225)
Fair Value Longer than 12 months	27,092	27,548
Unrealized Losses Longer than 12 months	(4,689)	(1,752)
Total Fair Value	176,778	185,961
Total Unrealized Losses	(7,127)	(3,977)
Equity Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	4,632	129
Unrealized Losses 12 months or less	(289)	(2)
Total Fair Value	4,632	129
Total Unrealized Losses	(289)	(2)
Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	145,054	158,284
Unrealized Losses 12 months or less	(2,149)	(2,223)
Fair Value Longer than 12 months	27,092	27,548
Unrealized Losses Longer than 12 months	(4,689)	(1,752)
Total Fair Value	172,146	185,832
Total Unrealized Losses	(6,838)	(3,975)
US Treasury Securities and Obligations of U.S. Government [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	1,990	15,005
Unrealized Losses 12 months or less	(5)	(4)
Total Fair Value	1,990	15,005
Total Unrealized Losses	(5)	(4)
Corporate Bonds [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	11,782	7,552
Unrealized Losses 12 months or less	(259)	(85)
Total Fair Value	11,782	7,552
Total Unrealized Losses	(259)	(85)
Collateralized Corporate Bank Loans [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	45,452	64,712
Unrealized Losses 12 months or less	(496)	(824)
Fair Value Longer than 12 months	4,087	8,898
Unrealized Losses Longer than 12 months	(314)	(1,091)
Total Fair Value	49,539	73,610
Total Unrealized Losses	(810)	(1,915)
Municipal Bonds [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	54,540	50,546
Unrealized Losses 12 months or less	(710)	(945)
Fair Value Longer than 12 months	22,994	15,684
Unrealized Losses Longer than 12 months	(4,375)	(656)
Total Fair Value	77,534	66,230
Total Unrealized Losses	(5,085)	(1,601)
Mortgage Backed [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	31,290	20,469
Unrealized Losses 12 months or less	(679)	(365)
Fair Value Longer than 12 months	11	2,966
Unrealized Losses Longer than 12 months		(5)
Total Fair Value	31,301	23,435
Total Unrealized Losses	$ (679)	$ (370)