Investments (Summary of Gross Unrealized Losses for Investments that have been Continuously in Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Investments [Line Items]
Fair Value 12 months or less	$ 93,662	$ 291,131
Unrealized Losses 12 months or less	(921)	(5,269)
Fair Value Longer than 12 months	43,554	28,890
Unrealized Losses Longer than 12 months	(2,483)	(5,604)
Total Fair Value	137,216	320,021
Total Unrealized Losses	(3,404)	(10,873)
Equity Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	6,569	6,584
Unrealized Losses 12 months or less	(364)	(838)
Fair Value Longer than 12 months	1,761
Unrealized Losses Longer than 12 months	(583)
Total Fair Value	8,330	6,584
Total Unrealized Losses	(947)	(838)
Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	87,093	284,547
Unrealized Losses 12 months or less	(557)	(4,431)
Fair Value Longer than 12 months	41,793	28,890
Unrealized Losses Longer than 12 months	(1,900)	(5,604)
Total Fair Value	128,886	313,437
Total Unrealized Losses	(2,457)	(10,035)
Us Treasury Securities and Obligations of U.S. Government [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less		41,428
Unrealized Losses 12 months or less		(61)
Total Fair Value		41,428
Total Unrealized Losses		(61)
Corporate Bonds [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	42,945	96,475
Unrealized Losses 12 months or less	(164)	(1,822)
Fair Value Longer than 12 months	2,694
Unrealized Losses Longer than 12 months	(29)
Total Fair Value	45,639	96,475
Total Unrealized Losses	(193)	(1,822)
Collateralized Corporate Bank Loans [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	10,252	65,868
Unrealized Losses 12 months or less	(69)	(1,758)
Fair Value Longer than 12 months	11,381	3,532
Unrealized Losses Longer than 12 months	(58)	(124)
Total Fair Value	21,633	69,400
Total Unrealized Losses	(127)	(1,882)
Municipal Bonds [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	16,102	44,525
Unrealized Losses 12 months or less	(282)	(488)
Fair Value Longer than 12 months	16,897	25,310
Unrealized Losses Longer than 12 months	(1,797)	(5,478)
Total Fair Value	32,999	69,835
Total Unrealized Losses	(2,079)	(5,966)
Mortgage Backed [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	17,794	36,251
Unrealized Losses 12 months or less	(42)	(302)
Fair Value Longer than 12 months	10,821	48
Unrealized Losses Longer than 12 months	(16)	(2)
Total Fair Value	28,615	36,299
Total Unrealized Losses	$ (58)	$ (304)