Investments (Summary of Gross Unrealized Losses for Investments that have been Continuously in Unrealized Loss Position) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Schedule of Investments [Line Items]
Fair Value 12 months or less	$ 112,276	$ 113,255
Unrealized Losses 12 months or less	(1,997)	(1,287)
Fair Value Longer than 12 months	45,974	53,634
Unrealized Losses Longer than 12 months	(2,522)	(2,613)
Total Fair Value	158,250	166,889
Total Unrealized Losses	(4,519)	(3,900)
Equity Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	144	316
Unrealized Losses 12 months or less	(60)	(2)
Fair Value Longer than 12 months	2,603	2,721
Unrealized Losses Longer than 12 months	(430)	(312)
Total Fair Value	2,747	3,037
Total Unrealized Losses	(490)	(314)
Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	112,132	112,939
Unrealized Losses 12 months or less	(1,937)	(1,285)
Fair Value Longer than 12 months	43,371	50,913
Unrealized Losses Longer than 12 months	(2,092)	(2,301)
Total Fair Value	155,503	163,852
Total Unrealized Losses	(4,029)	(3,586)
Us Treasury Securities and Obligations of U.S. Government [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	32,220	47,162
Unrealized Losses 12 months or less	(129)	(165)
Total Fair Value	32,220	47,162
Total Unrealized Losses	(129)	(165)
Corporate Bonds [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	5,603	5,649
Unrealized Losses 12 months or less	(263)	(56)
Fair Value Longer than 12 months	4,333	4,421
Unrealized Losses Longer than 12 months	(174)	(394)
Total Fair Value	9,936	10,070
Total Unrealized Losses	(437)	(450)
Collateralized Corporate Bank Loans [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	39,055	23,026
Unrealized Losses 12 months or less	(830)	(422)
Fair Value Longer than 12 months	3,682	6,968
Unrealized Losses Longer than 12 months	(27)	(67)
Total Fair Value	42,737	29,994
Total Unrealized Losses	(857)	(489)
Municipal Bonds [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	31,732	35,719
Unrealized Losses 12 months or less	(393)	(413)
Fair Value Longer than 12 months	31,119	34,684
Unrealized Losses Longer than 12 months	(1,410)	(1,562)
Total Fair Value	62,851	70,403
Total Unrealized Losses	(1,803)	(1,975)
Mortgage Backed [Member] | Debt Securities [Member]
Schedule of Investments [Line Items]
Fair Value 12 months or less	3,522	1,383
Unrealized Losses 12 months or less	(322)	(229)
Fair Value Longer than 12 months	4,237	4,840
Unrealized Losses Longer than 12 months	(481)	(278)
Total Fair Value	7,759	6,223
Total Unrealized Losses	$ (803)	$ (507)