Investments (Summary of Realized Gain (Loss) on Investments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Investments [Line Items]
(Loss) gain on investments	$ 3,188	$ 1,105	$ 5,679	$ 1,589
Change in unrealized losses on other investments	(228)		(731)
Other-than-temporary impairment	(850)		(4,257)	(2,888)
Net realized (losses) gains	2,110	1,105	691	(1,299)
Us Treasury Securities and Obligations of U.S. Government [Member]
Schedule of Investments [Line Items]
(Loss) gain on investments
Corporate Bonds [Member]
Schedule of Investments [Line Items]
(Loss) gain on investments	(107)	(81)	(125)	(1)
Collateralized Corporate Bank Loans [Member]
Schedule of Investments [Line Items]
(Loss) gain on investments	8	(98)	56	(116)
Municipal Bonds [Member]
Schedule of Investments [Line Items]
(Loss) gain on investments	120	(97)	204	(165)
Mortgage Backed [Member]
Schedule of Investments [Line Items]
(Loss) gain on investments	(1)	(1)	(1)	(1)
Equity Securities [Member]
Schedule of Investments [Line Items]
(Loss) gain on investments	$ 3,168	$ 1,382	$ 5,545	$ 1,872